290 TJic Anicyican Geologist. May. i898 
like projection a little removed from the glabella; e)'^es a little anter- 
ior to the middle and remote from the glabella; facial sutures extend 
from the eyes forward almost parallel to the sides of the glabella and 
backward with a double curve to the genal angle. 
Movable cheeks unknown as are also the other parts of the form. 
The description is based on one specimen excellently preserved. 
* 
Cheilocephalus st. croixensis, n. sp. 
Plate XVII, FiK. 1. Plate XX, Figs. 7 and 8. Plate XXI, Fig. 19. 
Size of head, width 25 mm.; length 16 mm.; marginal rim, width, 
i]/2 to 2 mm.; glabella length 15 mm.; width anterior 9 mm.; poster- 
ior 13 mm. 
Formation and locality: Upper Dresbach, Taylor's Falls. 
Genus Dicellocephalus, Owen, 1862. 
A number of specimens whose affinities were doubtfully referred to 
either Ptychoparia or Dicellocepalus were upon a comparison of the 
detailed descriptions of old^r sp;cies finally groupjtl und;r a sina^ie 
species D. misa Hall,* 1863. 
In a paragraph following the original description of this species an 
explanation is made by the author which throws a good deal of light 
upon these forms and accounts to a certain extent for the rather more 
than usual difficulty in identification. He says: "In species like this 
one, it is not easy to point out the characters which separate them 
from such forms as D. spiniger or D. pepinensis and we have the fea- 
tures of glabella intermediate between the more characteristic forms 
of Conoceph'xlites {Ptychoparia) and Dicellocephalus. In this 
one the glabella is more conical and the posterior glabellar furrows 
scarcely united across the summit." 
"The pygidium which occurs in several specimens associated with 
the glabella, has the prominent axis and broad lateral lobes with wide 
margin which are characteristic of Dicellocephahis and I am there- 
fore induced to place the species under that genus." 
Dicellocephalus misa Hail. 
Dikeloccphahis misa Hall. i6th Rep. N. Y. Mas. Nat. Hist., 1853, p. 14.^. 
Plate XX. Figs. 12 and IH. 
"Glabella prominent, somewhat conical, truncate at the apex, 
length about equal to width at base, which is more than one-third 
greater than the width in front. Three pairs of furrows are visible; 
the posterior ones oblique and sometimes slightly marked across the 
rniddle, leaving the posterior lobes deeply separated and directed for- 
ward at the extremities. Median lobes and furrows directed a little 
forward; anterior furrows faintly impressed, leaving a very narrow 
anterior lobe; occipital furrow well defined, straight in the middle, 
*i6th Rep. N. Y. Mus. Nat. Hist.. 1863, p. 144. 
