490 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



The first two segments of the thorax are about equal in length. 

 The third and fourth are slightly longer. The segments increase a 

 little in width from the first to the fourth. The last three segments 

 are abruptly narrower than the first four. The fifth, sixth, and seventh 

 are equal in length, and the last two bear each two spines near the 

 anterior margin, one on either side of the median line. The post- 

 lateral angles of the fifth and sixth segments are produced in a small 

 small spine on either side. 



The abdomen is composed of a single segment, narrow, elongate, 

 with the sides rounded and the posterior margin triangular between 

 the small post-lateral angles. At the base of the segment is a small 

 median spine. The uropoda are simple, single-branched, with each 

 branch composed of two articles. 



The legs are differentiated in two series. The four anterior pairs 

 are ambulatory; the three posterior pairs natatory. The legs of the 

 first four pairs are of different lengths. Those of the first pair are 

 the shortest, the second pair being somewhat more elongated. The 

 third and fourth pairs are greatly elongated, being many times longer 

 than the body, the basis, ischium, and merus being short, the carpus 

 and propodus enormously elongated. The carpus is 13 mm. long. 

 (In a larger specimen it is 21 mm. long and the propodus 26 mm. long.) 

 The last three pairs of legs are natatory, with the carpus and propodus 

 enlarged and fringed with long hairs. 



The operculum of the female has a longitudinal median keel or crest. 

 The fifth segment of the thorax on the ventral side has a conspicuous 

 median spine. There is a smaller one on the ventral side of the sixth 

 segment also. 



79. Genus EURYCOPE G. O. Sars. 



Body compact, depressed, oval in outline. Anterior division of 

 thorax less sharply marked off from posterior division. 



Head moderately large, deeply emarginate on either side of a 

 frontal process. First pair of antennae with multi-articulate flagellum. 

 Second pair of antennae elongated. Mandibles with molar expansion 

 and cutting edge divided into strong teeth. 



Four anterior segments of thorax short, subequal, transversely 

 excavated dorsally; the three posterior segments very large and 

 broad, convex. 



First pair of legs shorter than three following pairs, which are 

 subequal and very much elongated; natatory legs of similar structure 

 with dactylus distinct, and carpus and propodus expanded. Uropoda 

 small, double-branched, branches uniarticulate. 



See Sars for characters of genus, Crust, of Norway, II, 1899, p. 144. 



