62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 area separates the thickened, striated rim from the dorsal furrow

62

SMITHSONIAN MISCELLANEOUS COLLECTIONS

VOL. IO3

NO. 5

UPPER CAMBRIAN

TRILOBITES

—

^RESSER 63 be concave. Since the very heavyeye bandsare elevated,

most

of the fixigene

may

lie below the level bothof the dorsal

furrow and

of the eye.

The

moderate-size eyesvaryconsiderably in position. Libragene

unknown.

Pygidium

characterized by a stout axis in

which two

or

more

seg-

ments

are indicated.

The

axis is

from

a half to two-thirds the length of the

pygidium and

stands above the dorsal furrow. Pleural lobes

flat, extending fanwise into marginal spines. Pleural furrows strong

and

pleural grooves usually visible. Marginal spines usually rather blunt,

forming

a serrate edge.

As

the genus is

now

constituted they

number from

one tofive

on

^{a side,} dependingon the degreeof fusion.

ELLIPSOCEPHALOIDES ARGUTUS, new

species

Plate 10, Figures _5, 6

Several cranidia

from

the

Ram

Creek area retain sufficient of their characters to warrant description.

The

cranidium is broad.

The

almost parallel-sided glabella extends nearly the full length of the cranidium. In cross section itstands entirelyabovethe shallow dorsal

furrow and

the fixigenes

which

slope gently

down from

it.

The

occipital furrow is clearly defined both on the glabella

and

fixigenes,

and

three pairs of glabellar furrows are traceable.

The

fixigenes between'the eyes

and

the dorsal

furrow

are about as wide as the glabella at the

same

point. Unfortunatelythe eyes are not completely preserved,but appearto have been of normal size, shape

and

position.

Sabine formation; (loc. 12s)

Ram

Creek, 15 miles south of Canal Flats, British Columbia.

Holotype.—v. S.N M. No.

108735a; paratype. No. 108735b.

ELLIPSOCEPHALOIDES BRISCOENSIS, new

species

Plate 10, Figure ₇

One

of a dozen or

more

cranidia is figured. E. briscoensis is

narrower than E. argutus

from

the

same

region. Because of this featureitbridges the

gap

betweenthe genotype

and

the

narrow

forms.

The

glabella is rectangular with

rounded

anterior angles

and

has

two

or three pairs of glabellar furrows represented by elongate pits. In width the brim measures less than a fourth the glabellar length. It

has a peculiar

narrow

elevation in the middle,

and

also has a faintly defined

narrow

^rim.

As

a

whole

the brim is slightly convex

and

is set in a horizontal position.

On

the sides the brim passes into the anterior fixigenes

which

maintain its level. In fact the outer margins of the fixigenes are curved

up and

^back to the genal angles so that

04

SMITHSONIAN M

ISCEI-I.ANEOUS

COLLECTIONS

VOL. IO3 the ocular jilatforms are depressed, leaving the eye lobes in a promi- nent position. In this species the eyes are long,

and

the eye bands wide

and

heavy. Faint eye lines extend straight across the fixigenes slightly anterior to the second pair of glabellar furrows.

Sabine formation; (loc. 17s) Sabine Mountain, Brisco Range,

r>ritish Columbia.

Ilolofype.—

U.S.N. M. No.

108736.

ELLIPSOCEPHALOIDES SILVESTRIS, new

species

Plate it, Figures 1-3; Plate 12, Figure ₇

This form, intermediate between the broad

and narrow

species, is well represented in the collections.

The

nearly quadrate glabella is a little longer than wide

and

^is well

rounded

in front.

The

occipital ring is of even width.

The

fixigenes are less than half the glabellar width

and

maintain their width throughout.

The

simple brim, only alittle

narrower

thanthe fixigenes, hasan elongate bossinthemiddle.

A narrow

rim is faintly indicated for a short distance in the middle of the head.

Wide

eyelines connectthe

wide

eyelobeswath the dorsal furrow.

The

associated

pygidium

has a short

wide

axis on

which

three or four rings are demarcated.

The

pleural lobes

and

the rear border,

which

is as

wide

as the axis is long, have both pleural grooves and furrows.

Both

extend to the margin, producing sharp ridges. Five spines are developed on each side.

Honey Creek

limestone; (loc. 91b)

West Timbered

Hills,Arbuckle Mountains,

Oklahoma.

Holotypc.

— ^{U.S.N.M. No.}

^{108744a; paratypes,} Nos. io8744b-d.

ELLIPSOCEPHALOIDES SAWBACKENSIS, new

species

Plate ii. Figures 4, 5

Only

the

two

cranidia illustrated represent this distinctive species.

The

glabella is longer than

wide and

has three pairs of glabellar furrows indicated by pits.

The

fixigenes are about half the glabellar width

and

vary little

from

front to back.

Heavy

eye lines connect the large elevated eye bands withthe dorsal

furrow

ata point in front of the anterior pair of glabellar furrows.

The

^brim, about half the width of the fixigenes, is simple in structure but is raised as a boss in thecenter.

Lyell formation; (loc.

64X) Ranger Brook Canyon, Sawback

Range, Alberta.

//(//rt/y/'r'.—

U.S.N.M.

Xo. 108745a: paratype, No. _108745!).

NO. 5

UPPER CAMBRIAN

TRILOBITES RESSER 65

ELLIPSOCEPHALOIDES CARUS, new

species

Plate ii, Figures 7, 8

This isa small

form

associatedwith E. argutiis.

The

subcylindrical glabella is

rounded

in front

and

has three pairs of glabellar furrows.

The

fixigenes are

convex

in contrast to

most

other species; consequently the rather thin eye lines appear to be

more

curved than usual.

The

eyes are on slightly upturned heavy bands.

Sabine formation; (loc. 12s)

Ram

Creek, 15 miles south of Canal Flats, British Columbia.

Holotype.

— ^U.S.N.M.

Xo. 108747a; paratype, No. 108747b.

ELLIPSOCEPHALOIDES MONTIS, new

species

Plate ii, Figures 9-11

The

third species

from

the locality is an intermediate form, ap- proaching the

narrow

rather than the broad species.

Width may

be an aspect as

much

as a reality, since the narrowness in dorsal view

is sometimesduetothesloping position of the anteriorangles,whereas other species appear wider because the anterior flanges of the

same

size are

more

nearly in a horizontal position.

The

wide glabella of E. montis is well

rounded

in front,

and

has a slight indentation at the center. Glabellar furrows are reduced to faint pits.

The most

distinctive feature is the fusing of the broad eye line with the brim,

which

slopes back to the eyes, the latter being ina posteriorposition.

This gives the cranidium the appearance of being

made up

of the large glabella about

which

is draped a wide

band

that slopes toward the rear. Anterior fixigenes are eliminated

by

this juncture of the eye ridge

and

brim.

Between

the eyes

and

glabellathe fixigenes have just a little

more

than one-third the glabellar width. In this species theneck ring is rather wide.

Sabine formation; (loc. 12s)

Ram

Creek. 15 miles south of Canal Flats, British Columbia.

Holotype.

— ^U.S.N.M.

No. 108748a; paratype. No. 108748b.

ELLIPSOCEPHALOIDES BEARENSIS, new

species

Plate ii, Figure 12

An

imperfect cranidium represents the genus in the St. Charles formation of Idaho,

showing

that this element is also present in that fauna. This species is

much more

like the genotypein generalaspect, but differs distinctly

owing

to the

more

posterior positionof the eyes.

Glabellar furrows

seem

to lie lacking.

The

eye lines are verv mucli

66 SMITHSONIAN MISCELLANEOUS COLLECTIONS

VOL. IO3