REPORT ON THE AMPHIPODA. 955 



pcrason being a characteristic of }'outh and not of species. A specimen measuring, 

 without the antenna?, more than three-quarters of an inch, had no trace of a carina on 

 the first five segments of the peraeon. 



Locality.— Station 49, south of Halifax, Nova Scotia, May 20, 1873; lat. 43° 3' 

 N., long. 63° 39' W.; depth, 85 fathoms; bottom, gravel, stones; bottom temperature, 

 35°. Thirteen specimens. Dredged. 



Rhachotropis kergueleni, n. sp. (PI. LXXXV.). 



TJie Rostrum very long and narrow, depressed between the upper antennas ; the 

 lateral lobes of the head narrow, prominent ; segments of the perseon very short ; the 

 first four segments of the pleon long, carinate, dorsally produced into a small sharp tooth, 

 that on the second segment the largest ; on the first and second segments there is an 

 additional less prominent denticle on either side of the central one ; the postero-lateral 

 angles of the first three pleon-segments are not acute or produced ; in the third segment 

 the lower margin is straight, with several small submarginal spines, the lower lobe of 

 the hind margin is cut into fifteen upward turned teeth. 



Eyes not perceived. 



Upper Antenna'. — First and second joints long, subequal in length, the first thicker 

 than the second, carrying some long plumose cilia ; the second joint having many setules 

 on the upper and some spinules on the lower margin, and an apical feathered cilium ; 

 the third joint not a third of the length of the second ; the flagellum much longer than 

 the peduncle, of thirty-four joints, those of the distal half being very slender. 



Lower Antenna?. — The first three joints very short, the gland-cone short, decurrent; 

 the fourth joint much longer than the preceding three united, longer than the first joint 

 of the upper antennas, fringed above with setules, below with spinules and long 

 plumose cilia ; the fifth joint much longer than the fourth, nearly as long as the 

 peduncle of the upper antennas, fringed above with setules, and having a few spinules 

 on the lower margin ; the flagellum very slender, longer than the peduncle, abruptly 

 narrower, of thirty-seven joints, all slender, the first cleft at the base within the socket. 



Upper Lip. — The distal margin a little flattened, very slightly ciliated. 



Mandibles. — The cutting plate is narrow, with a small denticle at the top, the lower 

 end bidentate, although scarcely so in the left mandible of the specimen examined, 

 perhaps through its being worn down by use ; the secondary plate of the left mandible 

 with the edge cut into six small teeth ; the secondary plate on the right mandible is 

 narrow, with a very irregular edge, perhaps regularly dentate in unworn specimens ; 

 there are two spines in the spine-row, of which, however, on the left mandible only the 

 stumps remained ; the molar tubercle small, its dentate crown roundly oval, fringed with 

 strong sharp teeth, with rows of smaller denticles on the inner side, which do not appear 



