58 CARL BOVALLIUS, THE OXYCEPHALIDS. 



independent species, or identical with 0. pis cat or, is a question, which 

 I am not yet able to answer definitively, but I am much inclined to think 

 that the two are identical, as practically there are no differences to be 

 found in the description of STREETS. 



The head is somewhat longer and more depressed in the male 

 than in the female, in which the ocular region is tumid and rises con- 

 siderably above the dorsal line of the peraeon, a feature which seems 

 to occur, in a smaller or higher degree, in all the female forms in the 

 family, and which may thus be looked upon as a sexual distinction. In 

 the male the head is as long as the six first perseonal segments together, 

 in the female as long as the first five. The rostrum is scarcely half 

 as long as the rest of the head. 



The first pair of anlennce in the male are comparatively slender; 

 the first joint of the flagellum is about four times as long as it is broad 

 at the apex; the three following joints together are longer than the breadth 

 of the first flagellar joint. 



The perceon shows a very feeble median keel dorsally, and an al- 

 most evanescent lateral ridge on each side in the fully adult animal, in 

 the younger state the peraeon is perfectly smooth. 



The epimerals are long and deep, fully a third part as deep as 

 the height of the peraeon. 



The first pair of perceopoda (PL I, fig. 11) are much shorter 

 than the second ; the lower front corner of the carpus is a little protrud- 

 ing, but does not form a distinct heel as in the following species; the 

 carpal process is irregularly serrated, with broad teeth, and bordered by 

 very long, stout bristles; it is somewhat longer than the hind margin 

 of the metacarpus, which forms a thin serrated edge, with short trian- 

 gular teeth (PL I, fig. 12); against the rounded lower corner of this 

 edge the dactylus impinges, so that the first pair really have a com- 

 plexely cheliform hand (see above, p. 33). The second pair (PL I, fig. 

 13) have a very long cheliform hand, the carpus, without the process, being 

 half as long again as the metacarpus; the front margin of the carpus 

 runs in a line with that of the metacarpus, the lower corner not pro- 

 truding at all; the carpal process is serrated, bordered with a few short 

 bristles, and is considerably longer than the hind margin of the meta- 

 carpus, but does not reach to the apex of the dactylus. The third and fourth 

 pairs are equal in length and slender; along the hind margin of the 

 tibia and carpus there are some short spines. The fifth pair are the 

 longest; the femur is almost ovate, and as long as the three following 



