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



The remaining thoracic appendages, on the contrary, are abundantly furnished with 

 long, unbranched hairs, and short, stout, serrated, and smooth spines ; the latter are 

 especially developed at the distal extremity of each joint just before its articulation with 

 the succeeding joint. 



The proximal joint of the limb is the stoutest, and except in the two penultimate 

 limbs, the longest, its margin is clothed with fine delicate unbranched hairs ; the 

 second joint is shorter, and the third shorter still ; the fourth and fifth joints in the 

 posterior limbs are considerably elongated ; the distal extremity of the terminal joint is 

 separated ofi"by a suture, and ends in a sharp spine. 



The abdominal a2:'pendages present no peculiarities except the terminal uropoda, which 

 have been well described and figured by Studer ; ^ the endopodite becomes fused with the 

 protopodite, and is extraordinarily elongated ; the short exopodite is sj)ine-like, and can 

 be fixed at right angles to the rest of the appendage, forming in this way a defensive 

 apparatus, which, as Studer suggests, no doubt secures to the animal a greater freedom 

 from the attacks of birds and other enemies. B'or figures and fuller description of 

 this structure the above-mentioned Memoir by Studer should be consulted. The 

 structure of the uropoda in this species recalls that characteristic of the family 

 Sphaeromidse. 



Two specimens of Serolis latifrons dredged ofi" Possession Island in 210 fathoms 

 present some variations from all the other specimens ; they are both females, with fully 

 developed brood lamellae, and are approximately of the same size, measuring 28 mm. in 

 length by 23 mm. in breadth ; the proportions therefore of these specimens are nearly the 

 same as in the males of the typical Kerguelen form ; the sterna of the abdominal segments, 

 however, are quite like those in the females. In one specimen the posterior two pairs of 

 brood lameUse of the left side overlap those of the right, the two anterior pairs are normal. 

 This variety is quite difi"erent in colour, being of a uniform yellowish brown, with a few 

 scattered black spots, especially upon the caudal shield. The shape of the caudal shield 

 is difi'erent from that in the Kerguelen specimens ; it is considerably narrower, and the 

 lateral margins are almost straight, with only a very slight outward bulging ; the posterior 

 epimera of the body come therefore to project considerably beyond the margin of the 

 caudal shield, which is almost completely triangular in shape. 



One of the specimens is figured on PI. II. fig. 1, and may be compared with the 

 figures of Studer and Miers of the normal variety. 



Station 148, January 3, 1874; lat. 46° 47' S., long. 51° 37' E. ; 210 fothoms ; 

 bottom, hard ground, gravel, shells. 



Kerguelen Island, January 13, 1874 ; Cascade Bay, 5-40 fathoms. January 17, 

 1874 ; Royal Sound, 25 fathoms. 



1 Archivf. Naturgesch., 1879. 



