ISOPODS OF NORTH AMERICA. 275 



i have been able to ascertain that the species should be referred to 

 the genus Cassidisca. The outer branch of the uropoda is more than 

 one-thii-d as long- as the inner ])ranch, and in the dried specimen was 

 rather dithcult to tiiid. By careful!}' scraping- oft some of the incrust- 

 ing- substance the form of the uropoda was disclosed. 



The bod}^ is oval, depressed, about 5 mm. in length. 



The seven segments of the thorax are distinct; the tirst three are 

 subequal in length; the three following segments are subequal, and 

 are longer than the three preceding segments; the seventh segment is 

 a little shorter than the sixth segment. 



The first segment of the abdomen is short, about as long or perhaps 

 a little shorter than the seventh thoracic segment. I'he terminal seg- 

 ment is triangular with apex obtusely triangulate. The base of the 

 segment appears to have a large median longitudinal elevation or boss, 

 and a smaller one on either side. 



The inner branch of the uropoda is as long as the terminal segment; 

 the inner margin is straight; the outer margin is curved. The outer 

 branch is a little more than one-third the length of the inner ])ranch, 

 and is marked oft' only by a small incision in the exterior margin of the 

 inner branch. It is separated on the inner margin from the inner 

 branch only by a depressed line. In a fresh specimen the separation 

 might be more complete. 



Nothing can be ascertained of the antenna?. 



47. Genus TECTICEPS Richardson. 



Body oval and somewhat flattened. 



Head subquadrangular, l)roader anteriorl}' than posteriorly, with its 

 anterior and lateral margins produced, concealing the antenme. The 

 antennse, which are entirely hidden, extend l)ackward and lie under 

 the epimeral plates at the sides of the thorax. 



The first and second pairs of legs are subchelate in the male; only 

 the first pair are subchelate in the female; the tirst pair terminate in 

 a large oval hand and finger, bearing a small hook; the second pair in 

 the male terminate in a more irregularly shaped hand. All the other 

 legs are simple in structure. 



The terminal segment of the abdomen is triangular and entire, and 

 is pointed at the extremit}'. The uropoda are double branched and 

 lateral, and resemble closely those of the genus Sp/ui^roma. 



The second, third, and fourth articles of the palp of the maxillipeds 

 are produced in lobes as in the genus Exosphderorna. 



ANALYTICAL KEY TO THE SPECIES OF THE (iENUS TECTICEPS. 



a. First pair of anteniuie, with a flagellum of ten articles, extend to the posterior 

 angle of the first thoracic segment. Second jiair of antennie, with a flagellum of 



