Because of the curled growth lines and especially because of the preservation of long slender spikes extending well beyond the rim, this shell was considered the same. This species was confused with I. panniila, but there is Httle similarity. fieldensis is characterized by a rather well-developed diamond pattern on the older part of the shell, which is increasingly blurred towards the margins by increased prominence of the wavy growth lines. Very large specimens show the pattern somewhat interrupted in the outermost part of the shell by fairly strong growth lines.
It is clear that most, if not all, of the subgenera in Obolus and LingulcUa are valid genera, but these two names themselves are in question. However, it lacks the necessary constriction of the ventral valve at the apical end, tapering too slowly and evenly to be referred to Lingulepis. A smaller, more perfect ventral valve shows the true dimensions of the shell, and as the valve comes to a rather sharp point, the borders approach the apex as slightly convex lines.
There is some question as to the specific identity of specimens from both. The Middle Cambrian form of the Grand Canyon is an undescribed species. The sandstone specimens from locality 70 also represent a new species, but since most of the material Irom this.
Walcott's description emphasizes the radiating striae on the "outer surface" of the shell as the diagnostic feature.
8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 This species characterizes Honey Creek Hmestone of Oklahoma
Upper Cambrian, Emigrant; (loc. yz) about 2| miles southeast of Benders Pass, Silver Peak Range, Nevada. Middle Cambrian, Ross Lake shale; (loc. 35c) i mile east of Hector, Mount Bosworth; and (loc.63j) Popes Peak, i^ miles southwest of Stephen, British Columbia. 97 This species is characterized by the uprightness of the ventral valve so that the false area is approximately at right angles to the base of the shell.
Middle Cambrian, Ross Lake; (loc. 63J) Papežev vrh, i| miles south of Stephen; and miles east of Hector, Mount Bosworth, British Columbia. The calcareous nodules in the Ross Lake Shale contain a rich fauna, among which is a species of Wiuianclla, distinct from. Preservation in granular limestone, as opposed to partial flattening in shale, explains some of the differences that are apparent at first glance.
Middle Cambrian, Ross Lake; (loc. 63j) Pope's Peak, i^ miles south of Stephen; and miles east of Hector, Mount Bosworth, British Columbia.
GASTROPODA
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 China
It has the coarsest ribs, and differs further in that the ribs are angular while in other species they are rounded in outline.
14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 Helcionella sp
Grabau's original figures do not match each other, but the angle of view and the difference between the inner and outer molds would account for this. BilHng's type was not determined, but Walcott states that he compared the type with the specimen he had in 1891. Cobbold noted that this species did not conform to the requirements of ScencUa, but because it lacked the pronounced concentric rugosity , the reference to Helcionella was more difficult. .
The species is limited to the form at the first locality, which according to Dr.
NO. 10 CAMBRIAN FOSSILS, 4TH CONTRIBUTION RESSER I9 Atlantic Province
The genus appears to be valid for other species extending from the Lower Cambrian to the Devonian. In the earlier years, Hyolithes was confused with various squid genera, especially Orthoceras, but this confusion was cleared up long ago. Several authors attempted to classify the family, but none have completed the job.
Examination of many species shows that switching is conservation dependent and can be found in any species.
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97
CRUSTACEA
It will be noticed that Cobbold's generic description of St Nothcc agrees in every detail with that of Watsouelle Grabau.
24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 Stenotheca crosbyi (Grabau)
30a) i tnile onder Argenta, Big Cottonwood Canyon, Wasatch Mountains; en (lok.. 54a) Blacksmith Fork, Bear River Range, Utah.
UNCERTAIN POSITION UROTHECA Matthew, 1899
This species is referred to Coleoloides based on its shape and the presence of stripes.
AGNOSTIDA
C3J) Popes Peak, 1^ miles Middle Cambrian, Ptarmigan; (loc. C3J) Popes Peak, 1^ miles southwest of Stephen, and (loc.
TRILOBITA
I W., 4 miles southeast of Hennepin, Arbuckle Mountains, Oklahoma
The eyes are not parallel to the dorsal furrow, but form a wide angle with the axis. The cranidium is considerably curved laterally, which is accentuated by the pronounced downward indentation of the anterior angles of the rim. Longitudinally, the head is also strongly curved, the greatest curvature being in the front half.
Two species were added from Texas, and descriptions of eleven from the Appalachians are in press; consequently this is a well-represented genus of trilobites. The facial suture unites the dorsal groove in front of the eye, by which arrangement the anterior fixation is eliminated and the brim is caused to be a single strip not attached to the lixigens at the anterior angles. On the other hand, Irvingella has much larger eyes than Chariocephalus, the extra length being achieved by the posterior part of the palpebral lobes extending farther.
At the same time, the eyes are slanted outwards from the axis of the head. Chariocephalus tumijrons H.\ll and Whitfield, U. Upper Cambrian, Secret Canyon; Pogonip ^Mountain, White Pine county, Nevada. Ptychoparia lux Walcott, Smithsonian Alisc.. 97LowerCaml)rian, Mount Whyte; (loc. 6id) south-west slope Mount LowerCaml)rian, Mount Whyte; (loc. 6id) southwest slope Mountain.
Whitfield's original specimens of the genus are on small patches of rock with the types Ccdaria woosfcri. In other words, Dreshachia is characterized by the lateral shortening of the preglabellar region to only a line for the attachment of the Hbragenes that lies entirely anterior to the glabella. In addition to the genotype and species previously referred to as Millordia, several new species from the Appalachian Nolichucky Formation are in the press.
One cannot be certain that Hall's original type and the specimens figured by Walcott represent the same species. Upper Cambrian, Eau Claire; Willow River Falls, Trempealeau and other places in Wisconsin and Minnesota.
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 Oryctocephalus indicus (Reed)
A few widely scattered granules occur in the raised parts of the test, but appear to be much more numerous in exfoliated specimens. The associated pygidium is strongly arched transversely and has a fairly even border, with a large spine at the anterior angles. This species is characterized by a broad lip, a relatively long glabella, and the curved course of the anterior facial suture.
Only a few specimens have been obtained in a rather large collection, so this species appears to be rare. 10 CAMBRIAN FOSSILS, 4TII RESSER CONTRIBUTION 4I, characterized mainly by the well-developed anastomosing lines on the glabella and libragena. The dorsal furrow is both wide and deep, so that the glabella and cheeks next to it have considerable relief.
The pygidium is quite broad, the border of moderate width, and the posterior margin is apparently not incised. Upper Cambrian, Honey Creek; (loc. 9q) 15 miles northwest of Fort Sill and (loc. 91L') northeast of Big Baldy, Wichita Moun-. Upper Cambrian, Honey Creek; (loc. 91a) 4 miles southeast of Hennepin, West Timbered Hills, Arbuckle Mountains, Oklahoma.
The eye lines are heavy and the eyes prominent due to their upward position, but the palpebral lobes slope only moderately. The surface is highly decorated in the usual way, but the anastomosing line on the glabella and fixigenes has such a fine mesh. 97Upper Cambrian, Honey Creek; (loc.. Sgv) 4 miles south of Hen- Upper Cambrian, Honey Creek; (attract.
The pygidium resembles that of both PterocephaUa and the Saukinae, but does not fit. Careful search of the collections revealed a partial cranidium which also has affinities with PterocephaUa but cannot be placed in that genus. It consists of a large prominent, highly curved glabella, on which the posterior pair of furrows are represented by slight, backward-directed indentations.
