596 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvin. 



direction as the claws. It is of about the same diameter as the claws, 

 but considerably longer and carries at its tip a small curved spine. 



The rami of the third legs are some distance apart, but as the 

 exopods are closely appressed to the margin of the basal apron, this 

 brings their tips close to the bases of the endopods. 



The spines on the exopods of these legs are proportionally larger 

 than usual and parallel with the outer margin. 



The fourth legs are short and stout, and made up of four joints; the 

 basal joint is as long as the remaining three. Of these latter the 

 second is the longest and the fourth the shortest. 



The latter joint is triangular and so arranged that the three spines 

 which it bears and the two upon the distal ends of the second and third 

 joints are close together along the outer margin. These spines are all 

 the same size and each has a row of hairs along its outer margin. The 

 fifth legs are very minute and situated on the ventral surface just at the 

 base of the egg cases. 



Total length, 3.3 mm. Length of carapace, 1.1 mm. ; width of same, 

 1.1 mm.; length of genital segment, 0.9 mm.; length of abdomen, 1.2 

 mm.; length of egg strings, 2 mm. Number of eggs in each, 30. 



Color, a uniform yellowish white, lighter on the genital segment, 

 which is almost pure white. 



('pelamydis, the name of its host.) 



In his monograph, published in 1863, Kroyer described (p. 50) two 

 small females of this species which had been found on the common 

 bonito ( Gy/nnosarda jidamis). His description differs in a few par- 

 ticulars from that here given, the most noticeable one being the pres- 

 ence of double papillre at the posterior corner representing the fifth 

 legs. In the present specimens also the carapace and genital segment 

 are more nearly the same size, but otherwise the two lots are identical. 



It would certainly not be feasible to have two species, both from the 

 same host, and resembling each other so closely. The differences, 

 therefore, must be regarded as mere variations, found in many other 

 species also. Richiardi (1880) reports this species from the gill cavity 

 of the mackerel (Scomber scomhrus), while Bassett-Smith describes 

 (1896) a species which he calls C. scomberi from the gills of the same 

 fish. Again in 1901 T. Scott described and figured a C. scomh^i, in 

 this case a single specimen adhering to the inside of the gill cover of 

 a mackerel. 



Bassett-Smith's description is so meager as to be worthless for iden- 

 tification; in his figures the carapace is long and narrow and the fourth 

 legs have only three joints. But he has placed five spines in a row 

 upon the outer margin of the last joint and none on the second joint. 

 If this were the correct distribution it would be an anomaly indeed, 

 unlike anything known in other species. Scott does not describe the 

 species at all, but in the figure he has given the fourth legs are four- 



