44 
PALEONTOLOGY OF NEW YORK. 
into spines having a length nearly equal to the length of the pleurae them¬ 
selves. A spine similar to these, but shorter and relatively broader, is pro¬ 
duced in the axial line, thus making eleven spines in the pygidial fimbria. 
Some slight variation is noticeable in the form of these spines, but in typical 
examples, the ten lateral extensions of the fimbria are broad, short, flat and 
closely set, the apex pointed backward, the terminal lobe being shorter 
and linguiform. 
Hypostoma, elongate-sub-triangular; anterior angles auriculate, posterior ex¬ 
tremity sub-linguiform. Centrum convex, bounded posteriorly by a conspi¬ 
cuous sulcus. The postero-lateral pits on the centrum are joined by a faint 
groove. Surface covered with venate lines and fiiintly granulose. 
Surface Ornamentation. In the normal forms of this species the entire sur¬ 
face is covered with granulations which become quite strong on certain por¬ 
tions, viz., the axial region of the glabella and thorax, and the surface of the 
pygidial fimbria, where the granules become elongate and pustuliform, often 
crowded and more conspicuous than upon the surface of the shield itself. 
Upon the thoracic pleurae are single rows of low and inconspicuous pustules, 
which, in somewhat weathered specimens from the shales, often appear as 
shallow punctae. The occipital ring bears a strong central spiniform node, 
and the thoracic segments along the axial line, sometimes evenly rounded, 
are usually slightly angulated or nodose, the nodes becoming stronger toward 
the pygidium. The annulations of the pygidium are evenly rounded. The 
surface of the doublure is granulose. 
Variations from the type of Cryplims Booihii, Green, as diagnosed by its 
author, and as here described more at length, occur in a series of asso¬ 
ciated forms presenting a marked and persistent deviation in certain 
features. This is most noticeable in the character of the pygidial fimbria, 
but it appears that no variation has taken place in this feature without 
correlative variation in certain other respects. In many individuals of this 
sub-genus, particularly those occurring in the limestone layers in the Hamilton 
