26 BIOLOGICAL SURVF.Y OF 



ISOPODA ASELLOIDA 



DESMOSOMATIDAE 



Desmosoma lobiceps spec. nov. (fig. 13) 



Male : The body is nearly six times as long as wide. The 

 first four thoracic segments are as long as the fifth and sixth 

 combined. The second and third thoracic segments are 

 slightly wider than the others. The head is about two-thirds 

 as long as wide. From above it consists of two parts, a 

 semicircular hinder part and a quadrate anterior part which 

 is distinctly narrower than the posterior part. The frontal 

 margin has a distinct medial depression, giving the two-lobed 

 outline alluded to in the name lobiceps. The abdominal seg- 

 ment is oviform, rounded before and behind. 



The first antenna is about half as long as the head and 

 comprises five segments, of which the second is the longest 

 and the fifth the shortest. The second antenna is about twice 

 as long as the head and divided equally between the four- 

 jointed peduncle and the eight- jointed flagellum. The 

 peduncle segments in order of decreasing length are: 4, 3, 

 1, 2. The first leg has the epimere acutely produced at the 

 tip. The segments in order of decreasing length are : 2, 6, o, 

 3, 7, 4. The uropod has a quadrangular peduncle slightly 

 wider than long. The inner ramus is about twice as long- 

 as the outer and both are one-jointed. 



Female: The general appearance is almost exactly like 

 that of the male. The frontal margin of the head is evenly 

 rounded. The abdominal operculum has the posterior margin 

 nearly straight. 



Length: Male, 1.5 mm.; female, 2.0 mm. 



Type: Female, B 164; cotypes, B 165. 



Remarks : This species belongs in the group to which ]\Iei- 

 nert applied the generic name Eugerda. The present species 

 is chiefly remarkable in showing slight sexual differences as 

 compared with the marked differences shown by other Des- 

 mosomafa. It is the first member of its family to be reported 

 from New England. 



