Smithsonian miscellaneous collections

Most genera of Atriboniidae have no trace of a stolidium, nor even the slight protrusion of the valve margins seen in some species. In this family, the valves meet directly anteriorly and posteriorly, as in most genera of Rhynchonelloidea.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 3 1846), which in turn is senior synonym of Camarophoria King ( 1850)

ACKNOWLEDGMENTS

EXTERNAL MORPHOLOGY

SIZE

COMMISSURE

Therefore, the meeting angle of the valves helps to distinguish Atribonium from the genera most similar to it and closest in time. Functional importance.- The meeting angle of the anterior and anterolateral parts of the commissure is probably related to evolution.

PLICATION

A few examples include Sanjuania Amos (Mississippian), Paranorella Cloud (Permian), Novella Bittner, Rhynchonella retractifrons Bittner (Triassic), and the recent genus Neorhynchia Thomson among the Rhynchonellacea; Brachymimulus Cockerell (Silurian) in the Triplesiacea, Parenteletes R. King (Pennsylvanian-Permian) in the Dalmanellaceae, and Centronella Billings (Devonian), Pseudoglossothyris Buckman (Jurassic) and the modern genus Abyssothyris Thomtulace in the Territory.

COSTATION

At the specific level, strength and distribution of costs are important. general, their relative strength in folds or wings is important. The costae are relatively weak and developed only anteriorly in the Devonian Atribonium, but they are numerous and narrow in the Mississippian Sedenticella.

THE STOLIDIUM

In Stenoscisma Conrad, their beginning on. umbilical cords are important; in Sedenticellula Cooper, their relative strength and bifurcations distinguish species. gen., relative strength of costae on fold and flanks helps determine the species. Evolution.—Costae show progressive increase in strength throughout the evolution of the Stenoscismatidae, but they show no definite trend within the Atriboniidae.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 9

IO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 do with the free living habit of the adult stenoscismatid, it does not

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT II

12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 of the valves in several Devonian and Mississippian species of Atri-

DELTHYRIUM AND DELTIDIAL PLATES

INTERNAL MORPHOLOGY

THE CAMAROPHORIUM

The camarophorium is not simply a detached and elevated area of the valve floor, despite its probable function as a muscle attachment. The spoon or trough of the Camarophorium is usually narrowly separated from the hinge plate.

THE SPONDYLIUM

I48 was developed first in the history of the group, and then its plates were spread in the shape of the camarophorium, to provide more surface for muscle attachment. Taxonomic significance.—The presence of the camarophorium on the brachial valve, together with the spondylium of the pedicle valve, is diagnostic of the superfamily Stenoscismatacea.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT IJ

I48 tooth plates meeting at the floor exhibit a similar wedge-shaped insertion of the fused plates into the valve bottom. Therefore, a wedge insertion may mean that this septum originates from structures above the valve floor (i.e. dental plates or cardinal structures) rather than from the floor itself, and therefore must be secured to the floor by insertion.

MUSCULATURE

These Orthotetacea are definitely related to the Pentameroidea and the Stenoscismatacea, their only similarity being in the formation of the spondylium by fusion of tooth plates and consequent wedge-like insertion of the resulting septum duplex into the valve floor. Licharev (1936, p. 66) clarified this concept as applied to the Stenoscismatacea, and it means aseptum formed of two distinct plates.

20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 the entire inner chamber of the brachiopod shell probably was smooth,

22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 ing the shell narrowly, possibly against the confining action of sand or

HINGE PLATE AND CARDINAL PROCESS

CRURA

LOPHOPHORE

PALLIAL MARKINGS

Function.—The transverse veins that traverse the valve of the pedicle from the anterior edge of the median septum to the sides of the valve are likely to sit on a portion of the gonads (Williams, 1956, p. 272, etc.). NO.2 SUPERFAMILY OF BRACHIOPODIA STENOSCISMATACEA — GRANT 25 they are subject to clear phylogenetic trends that would be of major taxa- they are subject to clear phylogenetic trends that would be of greatest taxonomic value to previous generations, and patterns of which are unknown.

SHELL STRUCTURE

LIFE HABITS PEDUNCULAR ATTACHMENT

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 27 The sulcate genus Camarophorina includes individuals with the ped-

ORIENTATION

28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 of Stenoscisma probably assured that the shell settled beak foremost

SUMMARY

PHYLOGENY OF SUPERFAMILY STENOSCISMATACEA

FAMILY ATRIBONIIDAE

30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

STENOSCISMATACEA

STENOSCISMATIDAE

ATRIBONMDAE

TORYNECHINAE

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 31

FAMILY STENOSCISMATIDAE

I have "lateral support plates" on the spondylium (Stepanov, 1937), have "lateral support plates" on the spondylium (Stepanov, 1937), but the internal structures of the Permian genus Torynechus Cooper and Grant are exactly the same as those of Stenoscisma. Torynechus probably descended from Stenoscisma by reduction of the stolidium to a marginal rim, thickening to an uncinuli-shaped form, and by development of more numerous costae.

CLASSIFICATION HISTORY

34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 names based on Stenoscismatinae Oehlert ( 1887) were in general use

EVIDENCE

On the other hand, in the Pentameroidea the pallial sinuses are weakly impressed and their pattern for the whole group is not definitely known. Williams (1956) described the pattern of some pentameroids as lemniscate with multiple main trunks, in contrast to the rhynchonelloid pattern seen in Stenoscismatacea.

MEASUREMENTS

NO.2 SUPERFAMILY BRACHIOPODŽIC STENOSCISMATACEA GRANT 35start as two main vascular trunks that divide quite symmetrically, begin as two main vascular trunks that divide quite symmetrically and become thinner towards the edges of the shell.

KEY TO THE STENOSCISMATACEA

36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

Smooth shell

SYSTEMATIC PALEONTOLOGY

38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Pedicle valve flatly convex transversely, strongly flexed through

40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 shell attached to some object that kept it suspended above the sea floor

USSR

NO.2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 41Stem valve flat convex, slightly swollen just anterior to bill, Pedicle valve flat convex, slightly swollen just anterior to bill, strongly curved through sulcus, flanks abruptly bent towards; bill sharp, strongly curved to down or upright position; description short, clear but not sharp; posterolateral slopes slightly compressed; delthyrium small, triangular, constricted by a pair of small deltidial plates leaving small slit-shaped foramen. Brachial valve more strongly convex in adults, convexity normally fairly even, slight swelling near beak in some individuals; margins abruptly bent after commissure, producing flat anteriorly; bill short, obtuse, apexinside delthyrium.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 43 Table 1

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 43Table 1. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 45MichiganAlkali Co., Alpena, Mich.stone, Thunder Bay Quarry, Alpena, Mich. Brachial valve more convex transversely, less convex longitudinally, slightly swollen near posterior, fold prominent anteriorly, abruptly curved toward commissure on anterior flanks, more gently curved anterior to fold; bill short, round, apex within delthyrium, hidden by delta plates.

4 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Pedicle valve interior with dental plates converging to form spon-

LENGTH (MM)

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 51 Table 3

Occurrence and abundance. - Upper part of the Callaway Forma. of Danville, Montgomery County, Mo. 53 speci-. These specimens differ from the Indiana species of Hall and Clarke (here assigned to the genus Coledium n. gen.) in their smaller size, lower convexity, trigonal rather than oval outline, weaker costae starting further anteriorly, and especially in their geniculation of each valve to produce the characteristic flattened anterior of Aribonium.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 53 The range of variation between specimens that Fagerstrom assigned

I48ium: sessile inposterior for about 1 mm., raised on low median sepium: sessile inposterior for about 1 mm., raised on low median sep-.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 55

I48 short; delthyrium small, triangular, narrowed by a pair of short conjunctures; delthyrium small, triangular, narrowed by a pair of connected deltidial plates, leaving small elongate-elliptic apertures that only slightly pierce tip of beak; the posterolateral margins of the valve slightly overlap the narrow flange of the brachial valve. Interior of brachial valve with a short concave hinge plate slightly depressed to meet apex of intercamarophorial plate; camarophorium begins near apex of valve as median septum with narrow lateral projections widening anteriorly, completely separate from articular plate except for connection through intercamarophorial plate, curved ventrally on ascending septum, nearly flat posteriorly.

58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Table 7

Occurrence and Abundance.— "Upper Alpena Limestone". now Four Mile Dam) at FourMile Dam in Thunder BayRiver, Sec. Valve on peduncle flatly convex, with slight swelling anterior to bill, strong geniculate near anterior margin, abruptly bent toward commissure; beak long, suberect, tip acute, standing well away from brachial beak, providing sufficient space for delthyrium and small, connected deltidial plates; foramen narrow, cutting tip of bill; beak ridges sharp, relatively long.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 63 Table 9

64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 ing up to five on fold, one fewer in sulcus (normally an odd number

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 65 walls and internal structures, and prominent intercamarophorial plate

66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 therefore, their occurrence does not extend the known range of the

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 67

Pedicel valve strongly convex (in adults) beak thick, rather long, erect to strongly curved, pressed against brachial umbo of large adults; beak crests short, rounded; orifice small, narrowed by curvature of beak, apparently completely closed in adults.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 69 Table 11

Pedicle valve interior with thick tooth plates forming deep spondylium; tooth plates become thinner anteriorly; spondylium elevated on relatively high median septum duplex, extending anteriorly about one-third of valve length. Brachial valve interior with stout hinge plate, fimbriate knob-like cardinal process apex, crura extending from anterior margin; camarophorium formed by spreading of upper edges of high median septum duplex, apparently in contact with hinge plate posteriorly, extending anteriorly about one-third of valve length, reaching slightly longer anterior than spondylium; intercamarophorial plate thick, duplex, supporting underside of hinge plate from median line of camarophorium, extending anteriorly longer than edge of hinge plate; muscle and pallet marks have not been observed.

ABC D

Kutorga) in a less clearly demarcated fold, a much longer pedicle bill and slightly more pronounced bones, especially on the pedicular valve (C. ?sellahasonecostaoneax hip, weak or absent bones on the fold). and its less transverse outline. Cooper (1956b) placed Camarophoriasella (Kutorga) in the genus Psilocamara Cooper based on its smooth shell and high arch.

72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 clearly is a uniting of two dental plates that join to form a septum

Comparisons.—Sedenticellula is characterized by its usually flat shell with low folds and a shallow sulcus, numerous fine ribs which begin at or near the beaks and may increase in number anteriorly by intercalation and bifurcation. Torynechus Cooper and Grantalso has bifurcatingcostae, but is clearly distinguished from Sedenticellula by its noncinuliform exterior.

74 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 48

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 75 Table 13

Pedicle valve interior with double spondyl short, about one-fourth length of adult valve, normally stationary at valve apex, with sides converging laterally to form median septum elevating anterior part of spondyl; muscles and other signs are not observed. Pedicel valve moderately strongly convex transversely, strongly convex longitudinally; umbonal region somewhat inflated, wings relatively flat; beak short, open, straight to substraight; beak ridges gently rounded, barely distinct; delthyrium small, triangular, laterally compressed with small, triangular, detached deltidial plates, leaving elongate, slit-like apertures, partially filled with beak of brachial valve; posterolateral.

78 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 edges of valve flattened to form narrow lateral pseudointerarea as

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 79

Valve margins abutting except at posterolateral slopes where brachial valve margin slightly overlapping narrow flange of pedicle valve; concentric growth lines weak, closely spaced, some forming low laminae at wide intervals. Pedicle flap slightly raised in umbilical region, strongly convex longitudinally through sulcus, flanks relatively flat; beak weakly attenuate, suberect toerect, press day against brachialumbo in some spec-.

82 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Pedicle valve interior with dental plates strongly curved toward

8 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 85

The camarophorium of this genus differs from that of most other genera of Stenoscismatacea in that the edges of its trough are directly connected to the sides of the split hinge plate, whereas. The edges of the camarophorium in all genera of the superfamily are very close to the bottom of the hinge plate, and the Permian genera are almost untouched.

ABC D E

88 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 the two available references dealing with the genus Camarophorinella

Additional species.-Terebratula superstes Verneuil (1845), long included in Ccmtcrophoria or Stenoscisma, externally strikingly resembles C. Specimens from near Novgorodsk in the U.S.S.R. 48) has all the external features of the genus. However, they do not resemble Cyrolexis haquei or the Ural-Timan species of Tschernyschev's group IV.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 91 pedicle beak that normally presses too tightly to the brachial umbo to

92 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 slopes for overlap by edges of brachial valve, normally exposed by

94 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Table 16

Stenoscismatacea with incipient, well-developed or degenerate stolidium, beginning in the Middle Devonian to the Permian; early representatives small, smooth, or weak; Later representatives bigger, stronger, stronger. Pedicel valve somewhat inflated in umbonal region, flatly convex from wings, more strongly convex longitudinally through fossa, wing margins not reflexed; beak short to moderately long, substraight to erect, strongly appressed to brachial umbo in some species and some individuals; ridges normally pale, rarely sharp; delthyrium triangular, small; deltidial plates absent, or small, normally detached;.

96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Pedicle valve interior with dental plates converging to form deep,

34;tingi." The distinction from the four species is entirely based on the number of setae in the sulcus, which varies from two to five.

98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 would imply that these various forms diverge at the outset, that they

Brachial valve more strongly convex; umbilical region swollen, profile straight along fold ridge, strongly inclined to sides; bill blunt, apex within pedicle valve. Interior of brachial valve with camarophore beginning at apex, curved slightly ventrally on high median septum, septum extending anteriorly along base about one-third of valve length; troughs that extend further toward the front creating a concave front edge to the sep-.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT IOI Table 17

The brachial valve is more strongly convex, with the greatest longitudinal curvature in the region of the umbilicus; beak curved into a pedicle valve, apex hidden by deltoid plates. Brachial valve inside with a low cardinal process near apex, posterior to hinge plate; a carapace extending from the front edge of the hinge plate; camarophorium connected to underside of hinge plate by thin intercamarophorial plate supported on duplex septum high median;

104 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 potential in the stock, and probably indicates descent of Stenoscisma

Comparisons.— Coledium bozvsheri is characterized by its small size, transverse subpentagonal outline, moderate convexity, weak but distinct costae on the anterior of the fold, smooth flanks, short spondylium and short, strongly curved kamarophoria. The mesial sinus begins posterior to the middle of the valve, and rapidly deepens anteriorly and is produced into a lingual extension that deeply bends the margin of the brachial valve, with a single, ill-defined, rounded plication in the anterior portion.

106 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 shows as a dark line on the surface and the spondylium is often ex-

Pedicel valve evenly and moderately convex strongly longitudinally, flatly convex transversely, thicker in umbonal region; beak thick, only slightly attenuate, raised to slightly bent, not strongly depressed at brachialumbo, leaving room for small holes; the shape of the foramen and the possibility of modification by the deltidial plate is not observed. Interior of brachial valve with short undivided plate; cardinal process formed by the slight swelling of the tip of the plate, with weak longitudinal punctation for the attachment of the diductor muscles; camarophorium ele-.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT III Table 20

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT II3

Pedicular valve moderately convex transversely, strongly convex longitudinally through sulcus, greatest swelling in umbilical region. Interior of valve on peduncle with tooth plates converging at base near apex to form sessile spondylium rising about 1-2 mm.

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT WJ

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT IIO,

Additional descriptive notes.—Pedicle valve beak short and sharp, erect to slightly curved; delthyrium open, usually not completely filled with brachial umbo and not obstructed by deltidial plates; the foramen pierces the tip of the beak. However, variants of the Mississippi Valley population may have established themselves as separate species in the Mon-.

124 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 nearly as wide as they are long, but larger ones are more transverse

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 125

Despite the small collection, it is described because all major features are shown, the species is distinctive, and it is one of the few stenoscismatids known from the Pennsylvanian. This condition is reminiscent of Aribonium, but is not so highly developed as in any species of that genus; it is merely a rounding, rather than a strong geniculation of the two valves.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT I3I

The specimen illustrated by Walcott (1884) is smaller than the largest specimens of the species, and therefore the costae are poorly developed. collections from the same locality have slightly stronger and longer costae, and some have three instead of two. men in the collection, on the other hand, have weaker costae; some lack costae because they do not form until the shell reaches a length of almost 6 mm. Small and medium specimens are quite flat and can be slippery; larger specimens are convex and may have as many as three costae on the fold and one each flank.

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT I33

134 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Brachial valve more strongly convex, with greatest convexity about

NO.2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 135above Fort Gibson, Oklahoma. 15 copies), Yale Peabody Museum above Fort Gibson, Oklahoma. Inner part of the brachial valve with camarophorium relatively broad and transversely concave, curved longitudinally towards the pedicle valve, trough extending anteriorly for one-third length of the valve, slightly beyond the anterior extent of the median septum; hinge plate and crura not observed, due to coarse calcite crystallization of samples.

NO. 2 BKACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 1 37 Table 30

Valve interior of pedicle with small soft, elongate serrations parallel to sides of valve; Dental plates nearly parallel in relation to dependent teeth, converging near floor of valve to form deep spoon-shaped spondylium, united along midline to form low buttress septum rising in height slightly anteriorly , extending anteriorly about one-third the length of the valve. Interior of brachial valve with subtrigonal hinge plate striated or thickened at apex to form cardinal attachment for diductor muscles;.

140 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

Stenoscisma is the culmination of the development of the Stenoscismatacea. Its species shows the best development of the traits that characterize the superfamily, and its evolution appears to have embodied the dominant trends in the history of the superfamily. The stolidium is best developed in Stenoscisma species, although it is only sporadically present in some species (e.g.

142 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 pointed out to King the mixture of Greek and Latin roots in his spell-

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT I43

144 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

It is much smaller than 5\venustum (Girty); the outline is normally more transverse, the stolidium slightly shorter, the fold is proportionately higher, and the charges are much wider, less, and start further forward. Appearance and age. The species is abundant in the fossil-rich part of the Zechstein near Possneck, Germany (Late Permian according to Gignoux, 1955, p.214).

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT I47

148 septum high, thin, relatively short on the floor, but length increases with the septum high, thin, relatively short on the floor, but length increases with height, capped by a spoonful of camarophorium with an unusually wide median projection at the leading edge; intercamarophorial plate short, May.

150 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

Discussion. This species illustrates the extensive development of the stolidium and of internal features characteristic of the Permian genus Stenoscisma. Schematic drawings showing the possible course of the muscles are based on examples of this and other well-preserved species from the same area (Fig. 1).

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 1 53 to shape of outline of camarophorium, outwardly and ventrally bowed

154 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 lower level in the Permian, and it is doubtful that they are conspecific

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 1 55 levigate anterior and anterolateral surfaces, each costa there deeply

I56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Table 34

Stepanov (1937, p. 149) stated that the major difference between Septacamera and Camarophoria (i.e., Stenoscisma) is in transverse buttress plates that extend from the distal sides of the tooth plates and brace the spondylium to the valve walls. Tschernyschev (1902, text-fig.28) presented a clear illustration of a specimen of the type species, Camarophoria kutorgae Tschernyschev, broken longitudinally along the midline to show the spondylium and camarophorium.

I58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 snitskaya and Tetracamera Weller, the former with high and the latter

It is strongly plicated and has a high anterior fold, but the fold does not extend above the flanks and the sulcus is not deeply depressed. They appear to retain all the features of the genus except for the controversial lateral support plates of the pedicle valve.

SPECIES DOUBTFULLY STENOSCISMATACEAN

The following passage is relevant here: "I can say nothing about the internal structure of the shell. On the surface of the shell near the beak of the abdominal valve two strong diverging dark lines can be seen. The general trend in brachiopods is that the structures of the brachial valve are more conservative than those of the pedicle valve ( UlrichandCooper, 1936).A study of brachiopods suggests that the spondylium is a structure that is repeated in many groups.These considerations favor the alternative that C.

GENERA NO LONGER INCLUDED IN

164 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 the brachial valve that subsequently modified to form the camarophor-

BUCKMAN, S. S

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 169 Hamlet, B

I70 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 173

Observations on the rocks of the Mississippi Valley, which have been referred to the Chemung Group of New York, together with descriptions of new species of fossils from the same horizon at Burlington, Iowa. Some additional or imperfectly understood fossils from the Hamilton Formation of Ontario, with a revised list of the species therefrom.

EXPLANATION OF PLATES

I76 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Page

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 1 77

USNM 142061

178 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Page

NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA — GRANT 179 Page

YPM 23258

USNM 89565

184 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Page

USNM 142530

INDEX

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Camarophoria (cont'd.)

192 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 Stenoscisma (cont'd.)