918 THE VOYAGE OF H.M.S. CHALLENGER. 



Locality. — The specimens were all obtained at Kerguelen Island, the larger from a 

 depth of 25 fathoms, the small ones, which were numerous, from the surface. 



Remarks. — I was at first disposed to consider the small specimens a distinct species 

 from the larger ; the integument does not show the covering of spiny hairs which are 

 conspicuous on parts of the large specimens, the proportions of the peduncular joints of 

 the antennas are not the same, the number of joints in the flagella are very different ; on 

 the inner plate and palp of the first maxillae, on the inner plate of the second maxillae, 

 on the outer plate of the maxdlipeds, there are differences in the number of teeth or of 

 setae ; on gnathopods, peraeopods, and uropods there are similar differences of proportion 

 or of number of spines and spine-groups ; but all these distinctions explain themselves 

 very naturally and consistently on the hypothesis that the small specimens are the young 

 and the large full-grown. 



The species has a considerable resemblance to Atylus austrinus, Spence Bate, from 

 Sydney, but in that the " dorsal surface is not denticulated," though the specimen was 

 large, " ^§ths of an inch," and notably it differs from the present in having "posterior 

 pair of pleopoda naked, and considerably longer than the two preceding pairs." 



That the present species is the same as Atylus australis, Miers, cannot, I think, be 

 doubted, although Mr. Miers did not find the accessory appendage of the upper antennae 

 in any of his four specimens, and though he speaks of the maxillipeds as being five- 

 jointed, a description possibly suggested by the groove which runs across the base of the 

 outer plate of the maxillipeds. 



So far as I can judge from Mr. Haswell's description and figure of his Atylus 

 megalophihalmus, from Clark Island, Port Jackson, that is synonymous with the present 

 species. Mr. Has well speaks of it as very variable, " the size of the eyes and their 

 degree of approximation above, the length of the antennae, and the form of the gnathopoda 

 being all subject to considerable variations," remarks which would well apply to 

 A tyloides australis. 



Atyloides assimilis, n. sp. (PI. LXXVIL). 



Rostrum minute, lateral lobes of the head rounded, not very prominent ; third pleon- 

 segment having the postero-lateral angles produced, but only minutely. Animal closely 

 resembling Atyloides australis, Miers. 



Eyes situated close to the lateral lobes of the head, large, reniform, retaining their 

 dark colour in spirits. 



Upper Antenna;. — First joint thicker and a little longer than the second, second 

 thicker and a little longer than the third, all three with groups of setae on the lower 

 margin, one at the apex being long and spiniform ; flagellum of sixteen joints, several of 



