ISOPODS OF NORTH AMERICA. 



531 



The pleopoda are five pairs of large, broad, smooth, leaf-like, 

 double-branched appendages not concealed on the dorsal side by the 

 small epimeral plates of the abdominal segments, 

 from which they project in full view. The uropoda 

 are a pair of single-branched, simple appendages, 

 similar in shape to the branches of the pleopoda. 



The marsupium is formed of five pairs of incuba- 

 tory lamellas, which overlap- so as to completely 

 encompass the ventral surface of the body; the first 

 pair have the terminal lobe of the distal segment 

 small, but well defined. 



There are seven pairs of small legs, all similar in 

 size and structure; a high triangularly shaped ex- 

 pansion or carina is present on the basis. 



Color uniformly light yellow. 



Male, two and one-third times longer than 

 broad, with all seven segments of the thorax and 

 all six segments of the abdomen distinct. Eyes 

 present. Abdomen occupies one-fourth of the 

 entire length of the body. 



Only one specimen was found at Key West by Henry Hemphill. 

 Parasitic on Petrolisthes sexspinosiis (Gibbes). 



Type. Cat. No. 29094, U.S.N.M. 



88. Genus STEGOPHRYXUS Thompson.** 



Branchial parasites. 



Female with the sixth segment of the thorax greatly longer than any 

 of the other segments. 



Abdomen with all six segments distinct; lateral parts or pleural 

 lamellae not developed. 



There are five pairs of tri-ramous pleopods. 



Uropoda consist of a pair of small, rounded, oval bodies, between 

 which is a small conical process. 



Male with all the segments of the thorax distinct. 



Abdomen ovoid, without appendages or traces of segmentation. 



a See Thompson for characters of genus, Bull. U. S. Fish Comm., XXI, 1902, p. 56. 



PlG. 577. PSEUDIONE 



CURTATA. MALE, x 

 23. 



