ISOPODS OF NORTH AMERICA. 



225 



b 



Body oblong-ovate, nearly twice as long as wide, K) n]m.:ll» nun. 



Head a little wider than long, 3 mm. : 4 mm., with the anteriqi- mar- 

 gin rounded truncate and the posterior margin pi'oduced in three lo})es, 

 the middle lobe being deeper than and about twice as wide as the lateral 

 lobes. The eyes are entirely absent; no traces of them are to be seen. 

 The first pair of antenna^ are composed of eight articles and extend 

 to the middle of the tirst thoracic segment; they are separated at the 

 base by a distance of 1 mm. The second pair of antenniB are composed 

 of nine articles and extend only a little beyond the end of the tirst pair 

 of antennte. 



The first thoracic segment is 2 mm. long, about twice as long as any 

 of the three following segments, which are each 1 mm. long in the 

 middle of the dorsal surface. The fifth segment is li mm. in length. 

 The sixth segment is as long as the first — about 2 

 mm. in length. The seventh segment is 1 mm. 

 long — only half as long as the preceding segment. 

 The post-lateral angles of the first four segments 

 are but little produced. The post-lateral angles of 

 the last two segments are very much produced, 

 those of the seventh segment being more produced 

 than those of the preceding segment. The epimera 

 of the second, third, fourth, and fifth segments 

 extend to the post-lateral angles of their respective 

 segments. Those of the second and third segments 

 are rounded posteriorly. Those of the fourth and 

 fifth segments are obtusely pointed. The epimera 

 of the sixth and seventh segments are ver}^ acutely 

 produced and extend to the posterior margins of 

 their respective segments, but not to the post- 

 lateral angles. The first five segments of the abdomen are subequal 

 and all visible in a dorsal view, the first segment not being covered by 

 the last thoracic segment. The first two have the lateral parts pro- 

 duced in long acute processes on the underside, these processes not 

 being visible from a dorsal view. The lateral parts of the other seg- 

 ments are not produced. The sixth or terminal segment is as wide as 

 long — 5 mm.: 5 mm. — and is longer than all the five anterior segments 

 taken together — 5mm.:4:mm. It is triangular in shape, with apex 

 produced and rounded. The uropoda are shorter than the last aT)dom- 

 inal segment, the inner branch being the shorter." 



«The inner branch is probably broken in the specimen, for this branch is described 

 b}"^ Say as triangular, whereas it appears truncate in the specimen. 

 28589—05 15 



FlG.'2'29.— NEROCILA LAN- 

 fEOI.ATA. X 3. 



