FAUNA OF THE TRENTON GROUP. 
37 
wide at the front and 15-5 wide at the neck-ring. A somewhat 
smaller specimen from Cobourg, Ont., is 74 mm. long, 54 mm. wide 
at the genal angles; the cephalon is 22-5 mm. long, the glabella is 
17-5 mm. wide at the front and 13*5 wide at the neck-ring. 
Horizon and Locality, This species, so far as is known, confined 
to the Trenton, seems to be found 1 all through that formation, 
although especially common in the lower part. It occurs at the 
following localities, and will probably be found at numerous other 
places, especially in the Central States: Middleville, N.Y. (exact 
horizon not known) ; Roaring Run, East Martinsburg, N.Y. (in strata 
corresponding to the Crinoid beds of the Ontario section) ; and in 
Ontario at Belleville (Crinoid beds) ; Cobourg (Sponge beds at top 
of Trenton) ; Healy falls (Dalmanella beds at base of Trenton ) ; 
Trenton and Peterborough (Prasopora beds) ; Fenelon Palls and 
Kirkfield 1 (Crinoid beds, very common). The type was collected at 
Yankleek Hill, east of Ottawa, by Logan, but the exact horizon is 
not known. 
Genus, Ceraurinus Barton. 
Ceraurinus mar g mat us Barton. 
Plate XI, figure 6. 
Ceraurinus marginatus Barton, Bull. Mus. Comp. Zool., 54, No. 21, 
1913, p. 550, PI. — fig. 1. 
A cranidium which appears to belong to this species was found 
in the Collingwood at Craigleith. It is much smaller than the type, 
but has a similar border in front of the glabella, a short frontal lobe, 
rectangular glabella decreasing slightly in width at the front, and 
sharp glabellar furrows. 
The length is 11 mm., the width 23 mm. 
The specimen cannot be identified with either Ceraurinus scofieldi 
(Clarke) or C. trentomnsis Barton because the glabella does not 
expand forward. It differs from C , ioarus (Meek) in not having the 
basal lobes isolated. The partial coalescence of the posterior right 
glabellar lobe with the one in front of it suggests C. confluens Barton, 
but there is not so complete coalescence as in that species, the frontal 
lobe is shorter, and the basal lobes narrower. 
The finding of this specimen in the Collingwood suggests that 
the original specimen of C. margiimtus may have come from that 
formation. The type is without label as to locality other than 
“Ontario,” and 1 the colour of the matrix is very like that of the 
specimen here described. 
Horizon and Locality . Prom the lower part of the Collingwood 
limestone at Craigleith. Collected by E. J. Whittaker. 
