CRUSTACEA. Ill 



short, straight, extending from the anterior margin two-thirds the length 

 of the carapace. Anterior extremities very slightly gaping, the margin 

 sharply rounding 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- 



