92 G. F. MATTHEW ON ILLUSTRATIONS OF 
&c., observed, there are probably other species and possibly some of the forms which the 
writer has included as sub-species, or varieties of the species first described in the following 
pages, will hereafter, when the parts are better known, be found to be well defined species. 
Description of the Species. 
The preceding remarks will serve as a general guide to the relationship of the species; 
and is introductory to the following more detailed descriptions. At the risk of including 
some features that may be accidental, full descriptions of the form and aspect of the several 
parts of the head in the species examined, have been given. The descriptions have been 
arranged in a fixed order for convenience in comparing the parts of one species with those 
of another. 
In these pages I have described only the parts of the cephalic shield, between the facial 
sutures, reserving for another occasion a description of the movable cheeks, pygidia, hypos- 
tomes, and other parts, of which at present the majority cannot with certainty be referred 
to the species hereafter described. 
PARADOXIDES ETEMINICUS. (Figs. 7-12) 
The anterior margin is arched around the front of the glabella and thence to the extre- 
mity is straight. The summit of the fold is flat and divided from the glabella and the flat 
area of the margin by an abruptly descending slope ; the marginal fold is twice as wide at 
its extremity as it is in front of the glabella. The flat area is about twice as long in front 
as at the suture. The sinus at the suture is broad and open. 
The glabella is about one-sixth longer than wide ; it is narrowed toward the base, but 
in front expands and rises into a rounded dome, upon which the third and fourth furrows 
are sometimes only faintly impressed. 
Glabellar furrows.—The first two are strongly impressed and cross the glabella : the first 
furrow is arched backward in the middle and is most deeply impressed in the outer third, 
especially at the extremity. The second furrow as a whole is parallel to the transverse 
axis of the shield ; its outer third is convex forward, is deeply and sharply impressed and 
is arched backward to an impressed point on the glabella ; the middle third is more broadly 
marked and is convex backward ; the convexity of the outer third is directed forward. The 
third and fourth furrows are faint and are in pairs; the third furrow is moderately arched 
with the convexity forward ; it extends nearly one-third across the glabella, and is directed 
forward at an angle of about twenty degrees. The fourth furrow is parallel to the third, 
and extends about one-quarter across; in the adult it is about half way from the front of 
the dome.* Neither of these two furrows reach the outer margin of the glabella. 
The occipital ring is roughly rectangular in outline ; it is high behind and slopes gra- 
dually to the occipital furrow ; the posterior edge is straight for half its length, and inclines 
sharply forward ; at the extremities it is moderately arched vertically. The occipital furrow 


* I have used this term as a conyenient one to designate the larger anterior part of the glabella of Paradoxides 
included between its front and the second furrow. 
