ISOPODS OF NORTH AMERICA. 



65 



The 



2 mm. in 

 The sixth 



Fkj. 48.— Cyathura carinata. o, Mandible. 

 X 51|. b, Maxii.lii'kd. X 51|. c, First 

 maxilla. X 51f. 



are li miii. I()n^,^ The maxillipeds have a palp of two articles 

 palp of the mandibles is composed of three articles. 



The first, fourth, and fifth sej>-ments of the thorax are 

 length. The second and third seonients are li mm. long, 

 and seventh segments are each 1^ 

 mm, long. The epimera are long 

 and extremeh' narrow plates extend- 

 ing the entire length of the seg- 

 ments and not separated off by dis- 

 tinct sutures. 



The entire length of the abdomen 

 is 3^ mm., or a little less than one- 

 fifth the entire length of the body. 

 The first six segments are fused 

 into a single segment about 1^ mm. 

 long, which has no trace of suture 

 lines. The seventh segment or tel- 

 son is narrow, elongate, and rounded posteriorly. The peduncle of 

 the uropoda is as long as the superior branch and extends two-thirds 

 the length of the telson. The inner, lateral branch is placed at the 

 posterior end of the peduncle and is rounded posteriorly; it extends 

 the remaining third of the length of the telson and reaches the 

 extremity of that segment. The dorsal or superior l)ranch does not 

 arch over the telson, but lies directly upon its dorsal surface; it 

 extends to the end of the peduncle, is somewhat triangular in shape, 



narrow and elongate, with apex acute. 

 The first three pairs of legs are pre- 

 hensile. All the others are ambula- 

 tory in structure. The first pair are 

 larger and stronger than the two follow- 

 ing pairs, and there is a tooth on the 

 inferior margin of the propodus. 



Three specimens — one from Marco, 

 Florida, another from Cedar Ke3'S, 

 Florida, and a third from off South 

 Carolina — differ from the other speci- 

 mens in the collection, in having the 

 last article of the first pair of antennte 

 as long as the third; in having a 

 rounded prominence instead of a tooth on the propodus of the first 

 pair of legs; in having the anterior segments of the abdomen quite 

 apparent at the sides, though fused and not apparent in the middle 

 of the dorsal surface; in having the peduncle of the uropoda about 

 half the length of the telson instead of two-thirds itshnigth, the inner 

 branch being as long as the peduncle; in having the fourth, fifth, and 

 28589—05 5 



Fig. 49.— Cyathura carinata. a, First 

 LEG. X 114. 6, First antenna, x 20^. 

 c, Second antenna, x 20j. 



