ISOPODS OF NOKTH AMERICA. 143 



The first segment of the abdomen is entirely covered by the last 

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

 lowing segments are nearly 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 base 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 are 

 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 obtusely 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 2406, from a 

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

 females, are from between the delta of the Mississippi and Cedar Keys-, 

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

 National Museum, Cat. No. 32074. 



The females differ from the males only in the shorter second antennae, 

 which extend only to the posterior margin of the third thoracic 

 segment. 



EXOCORALLANA SEXTICORNIS (Richardson). 



Corallana sexlicvrnis RICHARDSON, Proc. U. S. Nat. Mus., XXIII, 1901, 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 behind 

 them. The first antennae have the basal joint large and dilated, with 

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

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

 teen to twenty-one joints reach the posterior margin of the third 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 



