REPORT ON THE AMPHIPODA. 681 



Fifth Perieopods. — The front margin of the first joint is here almost absolutely- 

 smooth for the upper two-thirds of its length, while in the other species it is spined 

 almost through its whole length ; on the other hand the cilia on the postero-distal 

 curve are here more numerous. The fingers in this species are less slender than in the 

 other. 



Phopods. — Two very small coupling spines, with a row of three back-turned teeth 

 along the margin ; the inner ramus with twelve, the outer with fourteen joints, the 

 first of the outer fringed as in the companion species with numerous plumose setae, the 

 first of the inner with the cleft spines three in number. 



Uropods. — In the first pair there are four spines on the margin of the outer ramus, 

 and five on that of the inner, leaving a comparatively small terminal portion free from 

 sj)ines ; in the second pair the outer branch has four, the inner three, spines ; in the third 

 pair the outer branch has three spines on one margin, and on the other one at the base 

 of the nail ; this branch is not longer than the peduncle, the other, which is much shorter, 

 has but one spine. 



Tel son. — This, though similar in the details of its structure to that of Hippomedon 

 hergueleni, is extremely difi"erent in its proportions, being in fact but little longer than 

 its greatest breadth. 



It is not very safe to establish new species upon small difierences in the relative 

 lengths of joints of the antennae and limbs, or upon variations in the number of spines 

 that form a marginal row, since these discrepancies and such as these may be due to age 

 or sex or individuality, but in the present instance it must be noticed that in regard to 

 the two forms named Hippomedon kergueleni and Hippomedon trigonicus, specimens of 

 the same sex have been compared, and that the more striking form of the fourth pleon- 

 segment, and the larger number of spines on the first and second uropods, belong to the 

 smaller, not to the larger species. 



Length, one-quarter of an inch without the antennae. 



Locality. — Kerguelen Island ; depth not specified. 



Remark. — The specific name trigonicus, triangular, refers to the shape of the hump 

 on the fourth segment of the pleon. 



Hippomedon miersi, u. sp. (PI. X.). 



Lateral lobe of the head produced into a rounded angle. Postero-lateral angle of the 

 second segment of the pleon slightly acute, of the third segment rounded. The fourth 

 segment with a dorsal depression, the sixth segment with dorsal ridges on either side 

 of the telson. 



There seemed to be a faint indication of eyes. 



