172 
PALEONTOLOGY OF NEW YORK. 
Echinocakis Whitfield:. 
PLATE XXIX, FIGS. 20, 21. 
EcMnocaris Whitfieldi, Clarke. Bull. U. S. Geol. Surv., No. 16, Hig-her Devonian Faunas of Ontai-io 
County, N. Y., p. 45, pi. ii, figs. 3, 4. 1885. 
Cephalothorax elongate, irregularly hemicordate; length of each valve some¬ 
what less than twice the width, greatest width through the center ; margin 
distinctly elevated. Hinge-line long, straight, scarcely equal to the greatest 
length of the carapace; curving gently outward toward the anterior extrem¬ 
ity, whence the margin is abruptly deflected in a straight line for a short dis¬ 
tance, and then sharply curved to the antero-lateral edge, which is also nearly 
straight, rounding to the ventral margin which is sub-parallel with the hinge, 
the posterior margin being truncate and slightly incurved. 
Nuchal furrow indistinct on account of the flattening of the specimen. 
Cephalic region relatively small, having less than one-third the width of the 
carapace; its surface is almost wholly occupied by a low node, well defined 
on its posterior margin, but becoming obsolete toward the hinge. The surface 
of this node bears a number of elongate pustules. Close upon the hinge are 
two small tubercles, the posterior of which probably represents the eye- 
node. 
The Thoracic region, near the hinge-line and just behind the nuchal furrow, 
bears three parallel, elongate tubercles, one above the other; and behind them, 
situated more ventrally, an indistinct transversely elongate node. A short 
ridge or carina takes its origin at the base of the cephalic node, near the 
antero-lateral margin, and passes obliquely backward nearly parallel to this 
margin, becoming rapidly obsolete. 
The Surface is marked by numerous low, scattered tubercles on the ventral 
and postero-dorsal areas. On the cephalic region the finer sculpture is 
minutely squamose, a feature not exhibited in other species of this genus. 
Abdomen unknown. 
PosT-ABDOMEN. The Same fragment of shale which contains the carapace also 
