108 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 42. 



The terminal segment is triangular with apex rounded. The dorsal 

 surface of both of these segments is covered with small tubercles. 

 The inner, imm^ovable branch of the uropoda extends to the tip of the 

 terminal abdominal segment; it tapers to a rounded extremity. 

 The outer branch is one-third the length of the inner 

 branch and is posteriorly rounded. Both branches are 

 furnished with hairs. 



Two specimens, both females, were col- 

 lected by Dr. Edward Palmer in 1910, at 

 Maron Lagoon, Madre, Mexico. They were 

 found in oysters in salt water. 



The types are in the United States Na- 

 tional Museum, Cat. No. 43193. 



The two other described species of this ge- 

 nus from the Atlantic coast of North America 

 are Cassidinidea ovalis (Say) and Cassidinidea 

 lunifrons (Richardson) from both of which the present species differs 

 in the more rounded apex of the terminal abdominal segment, and 

 in the presence of tubercles on the abdomen. It differs further from 

 C. lunifrons in the shape of the head and in the shape and position of 

 the outer branch of the uropoda. 



Fig. 2. — Cassi- 

 dinidea T U' 

 beeculata 

 Maxilliped 



Fig. 3. — Cassi- 

 dinidea TU- 



BEECULATA. 



Thied PLEO- 



POD. X 41. 



