196 
PALEONTOLOGY OF NEW YORK. 
has been somewhat distorted, and the test, which is extremely tenuous, 
broken by compression in the shales. A single individual shows the im¬ 
pression of the crown of a small mandible in the substance of the carapace. 
This organ, in every visible feature, is comparable to those already described 
under the species Echinocaris punctata (page 167). The crown is curved or 
lunate, and bears five denticles, of which the anterior is sharp and canine¬ 
like, the posterior broader and more closely resembling the grinding surface 
of a molar tooth. Its length is 5 mm. 
Abdomen. In a single example the carapace is in close association with scat¬ 
tered somites of the abdomen, of which three are detached and the fourth 
is in articulation with the telson. One is quite broad, being twice as wide as 
long and somewhat elevated in the middle," the margins very, slightly ele¬ 
vated and faintly produced in the axial line; another is relatively longer but 
quite imperfect; a third about one-half longer than wide, and the posterior 
somite twice as long as wide, and nearly cylindrical. 
Post-abdomen composed of a small caudal plate, whose entire dorsal surface is 
occupied by the base of the telson, and is strongly elevated, the spine itself 
being stout and sub-conical. The cercopods, in their normal condition, are 
laterally flattened and slightly longer than the telson. 
The Surface of both abdomen and post-abdomen bears an ornamentation 
of elevated, anastomosing and slightly undulating lines, similar to those upon 
the carapace, but more conspicuous. These lines appear to be sharply angu- 
lated along the axis of each somite, and directed thence posteriorly over the 
lateral portions. 
Dimensions. All the carapaces observed are of about the same size, A 
well-preserved individual measures 48 mm. in length including the prora, 
which is 6 mm. long. The greatest width of one-half the carapace, as com¬ 
pressed, is 16 mm. Of the abdomen one somite measures 5 mm, in length 
and 10 mm. in width; another, 7 mm. in length and 5 mm. in width, and 
the posterior somite 10 mm. in length and 5 mm. in width. The telson is 
15 mm., and the cercopods each 17 mm. in length. 
