ISOPODS OF NORTH AMERICA. 148 



The first scguient of the abdomen is entirely covered b}- the last 

 thoracic segment, except a small portion in the middle. The four fol- 

 lowing- seo-ments are nearh' subequal in length. The first two (the 

 second and third) have a single transverse row of small tubercles close 

 to the posterior margin. The fourth segment has a double transverse 

 row of tubercles, the posterior row of tubercles being larger. The 

 fifth segment has three transverse rows of tubercles, the middle row 

 being the largest. The sixth or terminal segment of the abdomen is 

 triangulate, with apex rounded and furnished with four spines. There 

 is a lateral incision on either side, a little below the middle transverse 

 line. At the l)ase of the segment is a transverse row of small tuber- 

 cles. Below this row are two groups of three tubercles each, a group 

 on either side of the median line. There are also two small tubercles 

 on either side of the segment just above the insertion of the uropods. 

 On the posterior part of the segment is a double longitudinal line of 

 small tubercles, one row on either side of the median line. Lateral to 

 .these tubercles is a setose area, one on either side. The uropoda ai"e 

 as long as the terminal segment. The inner branch is twice as wide as 

 the outer branch and is truncately rounded and furnished with spines 

 on the posterior margin. The outer branch is obtiiselv pointed. Both 

 branches are furnished with hairs, as well as the terminal segment of 

 the abdomen. 



The type, a male, is from the Gulf of Mexico, station 2-iOO, from a 

 depth of 26 fathoms. Seven other specimens, all males, and thirteen 

 females, are from between the delta of the Mississi})pi and Cedar Keys, 

 Florida, and from the Gulf of Mexico. The type is in the U. S. 

 National Museum, Cat. No. 3207-1. 



The females differ from the- males only in the shorter second antenna', 

 which extend only to the posterior margin of the third thoracic 

 segment. 



EXOCORALLANA SEXTICORNIS (Richardson). 



Corallann sexiicornis R'ichardson, Proc. U. S. Nat. Mus., XXIII, 1!H)1, p. 518. 



Locality. — Key West, Florida. 



Head in the male ornamented with four spines, forming two trans- 

 verse series of two spines each, the first two being small, the second two 

 very large and long, much longer than the first two and situated ])ehind 

 them. The first antenna' have the l)asal joint large and dilated, with 

 a spine projecting outward from the inner exposed angle; the flagellum 

 consists of eight joints. The second antenna? with a flagellum of nine- 

 teen to twenty-one joints reach the posterior margin of the tliird tho- 

 racic segment. The head of the male is excavate above and deeply 

 sunken below the level of the dorsal surface of the body. The head 

 of the female is unornamented, with only a slight indication of two 

 small tubercles in the place where the large spines are situated on the 



