CRUSTACEA. 
177 
short, straight, extending from the anterior margin two-thirds the length 
of the carapace. Anterior extremities very slightly gaping, the margin 
sharply roimding in front, passing in a broad curve obliquely to the postero¬ 
lateral region, whence it passes in a gentle curve or a direct line to the 
hinge. The type specimen is so incomplete that the posterior outline can 
not be accurately determined. The entire margin is elevate and carinate. 
Nuchal furrow distinct, taking its origin on the hinge at about one-third 
its length from the anterior extremity and passing obliquely forward. 
Cephalic region small, sub-triangular on each valve and entirely occupied 
by a strong elevated node, the surface of which is covered with scattered 
tubercles, but it is impossible to determine which of them has served as 
the optic node. 
Thoracic region just behind the nuchal furrow marked by a single, strong, 
obliquely elongate dorsal node, bearing a tubercle near the hinge-line. This 
node, at its inferior extremity, comes almost into contact with a nodiform 
ridge, directed obliquely backward and produced into a lateral carina, which 
is parallel to the ventral margin of the carapace. Postero-dorsal area smooth, 
broadly and evenly convex. 
Surface obscurely punctate. 
Abdomen. Portions of the last three somites are to be seen in one of the type 
specimens. Each of these is short, sub-cylindrical, the posterior segment 
being a little the longest. The anterior margin of each is elevated into an 
articulating ridge, and the posterior margin into a spiniferous ridge. Upon 
the dorsal surface the spines on each somite appear to have been very short 
and scarcely more than elevated tubercles, but on the lateral surface were 
quite strong. There appears also to have been a spine on the lateral surface 
of each somite between the anterior and posterior margins. 
Post-abdomen. The caudal plate on the dorsal side is sub-pentagonal, depressed 
on the postero-lateral areas. The telson begins as an elevated ridge near 
the anterior portion of the plate and is produced to a length probably equal- 
