ISOPODS OF NOETH AMEEICA. 



75 



segment long, Ungulate in shape, rounded posteriorly with crenulate 

 margin. Outer branches of the uropoda arch over telson, but do 

 not meet in center; narrow, elongated. Inner branches of the uro- 

 poda extend beyond telson, are rounded posteriorly, and shorter 

 than peduncular joint; inner margins crenulate. Abdomen about 

 equal in length to fifth and sixth thoracic segments taken together. 



First pair of gnathopods large, sub- 

 chelate; second pair of gnathopods and 

 first pair of pereiopods subchelate, 

 small. Other pereiopods ambulatory, 

 slender. 



One specimen (type) sent by Mr. F. 

 Stearns to the U. S. National Museum 

 comes from between Nassau and 

 Andros Island, Bahamas. Another 

 specimen was taken by the U. S. 

 Bureau of Fisheries steamer Albatross off Cape Catoche, Yucatan. 

 . Cat. No. 23900, U.S.N.M. 



FIG. 60.. CALA- 

 THUKA CRENU- 

 LATA. FIRST 

 GNATHOPOD. 



FIG. 61. CALATHU- 

 RA CRENULATA. 

 ABDOMEN. 



17. Genus PARANTHURA Bate and Westwood. 



Segments of abdomen distinct in both sexes. First pair of antennae 

 have the flagellum multiarticulate in both sexes. Second pair of 

 antennae in both sexes have a rudimentary flagellum consisting of a 

 single article. 



Mouth parts as in Calathura. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS PARANTHURA. 



a. Flagellum of first pair of antennae composed of nine articles. First three segments 

 of thorax of equal length; the three following subequal and each one-third 

 shorter than either of first tw.o. First five segments of abdomen one-half the 

 length of seventh thoracic segment. Last abdominal segment funnel-shaped; 

 posterior margin coarsely denticulate and truncate. 



Paranthura infundibulata Richardson 



a'. Flagellum of first pair of antennae composed of six to seven articles. First five 

 segments of thorax of equal length; sixth segment somewhat shorter than any 

 of preceding segments. First five segments of abdomen as long as seventh 

 thoracic segment. Last abdominal segment long and narrow, rectangular in 

 shape, with margins entire Paranthura verrillii Richardson 



