PART 1 GARTH : PACIFIC OXYRHYNCHA 283 



Chelipeds in the adult male enlarged [i. e., elongated], with the 

 palms broadened and compressed. First pair of ambulatory legs markedly 

 the longest. 



Abdomen in both sexes consisting of seven distinct segments. (Alcock, 

 modified, of Scyramathia). 



Range: Eastern Pacific: from 5 miles south of San Benito Islands, 

 Lower California, to Gorda Banks, Gulf of California, Mexico; Galapa- 

 gos Islands; western Atlantic: from off Nantucket Shoals, Massachusetts, 

 to Cape Horn. Occurs also in the eastern Atlantic, Mediterranean, 

 Indian and western Pacific oceans as far north and east as Japan. 40-633 

 fathoms. 



Remarks: Evidence that the genus formed by uniting Anamathia, 

 Rochinia, and Scyramathia, as above, may be diphyletic is to be found 

 in the male first pleopods. Those of Rochinia gracilis (Atlantic), R. 

 cornuta, and R. occidentalis (see Plate Q, figs. 6, 7) resemble that of 

 Pisoides, while that of Rochinia vesicularis (see Plate P, fig. 6) resem- 

 bles those of Scyra and Chorilia (=Hyastenus) . Unfortunately, their 

 separation cannot be accomplished along the lines suggested by their 

 earlier synthesis, for the pleopods of both Rochinia rissoana (type of 

 Anamathia) and of Rochinia carpenteri (type of Scyramathia) , as shown 

 by camera lucida drawings provided by Dr. Isabella Gordon of specimens 

 in the Norman collection (British Museum), are of the first or pisiform 

 type. Rather, it will be necessary to examine the male pleopod of each 

 of the Rochinia species on a world-wide basis in order to determine which 

 of them should be united with R. vesicularis in an independent genus, a 

 task that lies beyond the scope of the present work. Thus in due time, the 

 superficial resemblance of Scyramathia to Hyastenus noted by Sars 

 (1885, p. 6) and to Pugettia, which has a scyriform pleopod although 

 belonging in another subfamily, noted by Alcock (1895, p. 202) will 

 have received structural confirmation. 



Key to the Pacific American Species of Rochinia 



la. Median tubercles 3; gastric 3. Rostrum longer than one-half 

 remainder of carapace. Pleopod pisiform . . cornuta 

 lb. Median tubercles 4; gastric 4. Rostrum shorter than one-half 

 remainder of carapace 



2a. Two spines on basal antennal article; an oblique row of 

 3 spines from the anterior median gastric spine to the margi- 

 nal branchial spine. Pleopod scyriform . . vesicularis 

 2b. One spine on basal antennal article; an oblique row of 

 5 spines from the anterior median gastric spine to the 

 marginal branchial spine. Pleopod pisiform . occidentalis 



