58 SMITHSONIAN* MISCELLANEOUS COLLECTIONS VOL. IO3

NO. 5

UPPER CAMBRIAN

TRILOBITES RESSER 59

bows outward

slightly. Several pairs of recurved glabellar furrows are visible.

The

occipital furrow, both on the glabella

and

fixigenes, is deeply impressed. In cross section the cranidium is convex, reach- ing the greatest curvature as the

median

line is approached. Longi- tudinallytheconvexityisless,

and

the rateof curvature even through- out.

The brim

width is a little

more

than one-fourth the glabellar length,

and

is a simple

convex band

surr6unding the front of the head.

The

associated

pygidium

is also convex, with a broad, faintly outlined axis

and

fused pleural lobes.

Davis formation; (loc. g2d) Federal

Lead Mine No.

4, Flat River, Missouri.

Holotype.

— ^U.S.N.M.

No. 108740a; paratypes, Nos. io874ob-d.

BYNUMINA MISSOURIENSIS, new

species

Plate 10, Figures 23-26

This is the

more common

Missouri species,

and

^it differs

from

B. caelata mainly in its

narrower

rim.

B. missouriensis has a tapering glabella, but the curvature of the lateral dorsal furrows is not even. It

expands

rapidly as far forward as the firstglabellar furrow, then suddenly begins to contract, main- taining a nearly straightcourseuntil it approachesthe anteriorangles,

where

the rate of taper

becomes

less again. Besides this peculiarity, the species is characterized

by

a rim width of a little

more

than one- fifththe glabellar length.

Davis formation; (Iocs, iik, giy) Flat River, Missouri.

Holotype.

— ^U.S.N.M.

No. 108741; paratypes, Nos. 108742a, b.

STENOPILUS

Raymond, 1924

STENOPILUS BACCA, new

species

Plate 10, Figures 8-13

Such

a featureless hemispherical trilobite as Stenopilus is difficult to describe. Several species are here presented, chiefly to

show

the differences between small

and

large examples,

and

the variation in degree of sphericity.

There

seems to be ^little doubt but that these trilobites developed

from

a Kingstouiaancestor.

Large

cranidia of S. hacca are nearly hemispherical ⁱⁿ shape, but, as

may

be seen in figures 10

and

.11, small heads

show

a distinct Kingstonia shape.

Of

course, the indentations of the dorsal

furrow

in the rear remain, but unless the very

convex

specimen is specially posed, they areobscured

by

the bulging cranidium.

60

SMITHSONIAN MISCELLANEOUS COLLECTIONS

VOL. IO3 Signal ATountain formation; (Iocs. I2i, j) 2 miles southwest of .Signal Mountain, Wichita Mountains,

Oklahoma.

Holotypc.

— ^U.S.N.M.

No. 108737; paratypes Nos. ^io8738a-c.

STENOPILUS ADUNCUS, new

species

Plate 10, Figures 14-17

A

second species is chosen for description to

show

the elongate

form

taken hy species of Stcnopilus. This development recalls the

Bymimia

elongation of the Kingstonia stock, but in Sienopilus this attends obesity

and

elimination of all furrows.

As

a result a snujoth trilobite is developed, so

convex

that the glabella overhangs the posterior margin. This high convexity is reduced forward, but the curvature is not eliminated in

any

portion of thetest.

6^. adiiuciis is longer than wide

and

has its greatest convexity at the rear. Otherwise it is practically featureless.

Signal

Mountain

formation; (loc.

12L)

Pickens Ranch,

Arbuckle

Mountains,

Oklahoma.

Hololypc.

— ^U.S.N.M.

No. 108739a; paratype,

No.

108739b.

BLOUNTIA

Walcott, 1916

BLOUNTIA PLANA, new

species

Plate 14, Figures 12-14

Only

pygidia have been assigned to the species.

While

the long axis is defined,

and

the usual interrupted axial furrows are visible, it does not stand abovethe pleural lobes.

The

chief characteristic of the species is

found

^{in the} flatness of the pygidium.

When

viewed

from

the rear, the pleural platforms, with the axis,

form

only a slightly

convex

shield.

The

border is slightly concave, thereby in- creasing the curvature near the lateral margins.

Sullivan formation; (loc. 64c) Glacier

Lake Canyon

Valley, 48 miles northwest of

Lake

Louise, Alberta.

Holotypc.

— ^{U.S.N.M. No.}

^{108779a; paratype,} No. 108799b.

BLOUNTIA

KINDLEI,

new

species

Plate 14, Figures 27-31

Two

small pygidia

and

a portion of the cranidium are figured.

A

somewhat

brokenpygidia is included to

show

appearanceof the test

;

one

much

larger

pygidium

has not been figured. This species,

which

is

named

in

honor

of the collector. Dr. Cecil Kindle, is typical of the genus in every respect.

NO. 5

UPPER CAMBRIAN

TRILOBITES RESSER 6l

The

large glabella tapers at a normal rate to the

rounded

front. It lacks furrows

and

even the occipital

furrow

is very faint.

The

fixi-

genes average less than half the glabellar width, expanding to the moderate anterior angles,

and

behind the eyeinto stout posterolateral limbs.

Eyes

are small, situated about the midpoint of the cranidium.

The

ratherheavy,

somewhat

upturned rim isaboutthe

same

width as the preglabellar area.

When

exfoliated, the

pygidium shows

a long axis on

which

at least six rings are faintly indicated.

As

a whole,the

pygidium

is triangular in outline. In cross section the curvature is gentle, except near the margins

where

the slope increases so

much

thatthe outer edgesare slightly turned under.

Warrior

limestone; (loc. 38e) i mile northwest of Benore, 5 miles west of State College. Pennsylvania.

Holotype.—U.S.'NM.

No. 108788a; paratypes, Nos. 108788b, c.

BLOUNTIA

(?) DISPARILIS,

new

species

Plate 14, Figures 10, 11

This

narrow

cranidium is not typical of Blountia.

The

glabella tapers to a

rounded

anterior outline

and

lacks glabellar furrows.

A

shallow occipital furrow separates a

narrow

neck ring.

The

fixigene

isnarrow, averaging aboutone-third the averageglabellarwidth.

The

wide brim is subdivided into a preglabellar area

and

a widerrim.

The

rim is thickened

and

increases in the middle to about twice the width of the preglabellar area.

Eyes

small. Longitudinally the cranidium attains considerable convexity by rather strong curvature in the rear portion. In cross section the curvature, including the posterolateral limbs, is

more

even.

Sullivan formation_; (loc. 64h) Glacier

Lake Canyon

Valley, 48 miles northwestof

Lake

Louise, Alberta.

Holofype.—lJ. S.

N.M.

^No. 108775.

BLOUNTIELLA

^Resser, 1938

BLOUNTIELLA ALBERTA, new

species Plate 14, Figures 19-26

Although

this species is represented by

numerous

cranidia, the

pygidium

has not been located.

Taken

as a whole, the cranidium is

rather short,

and

the glabella occupies

most

of its cranidial area.

Glabellar furrows are lacking even in exfoliated specimens.

The

fixi-

genes average less than half the glabellar width.

The

eyes are small, situated about the midpoint of the cranidium.

A narrow

preglabellar

5

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VOL. IO3