208 IBLA QUADRIVALVIS, 



namely, about half down the peduncle. I may state, for 

 the sake of comparison, that the hermaphrodite to which 

 this individual was attached, was, including the peduncle 

 and capitulum, one inch in length, that is, six times as 

 long as the male, and one fifth of an inch in width, that 

 is, four times as wide. The above measurements show 

 that the male of this species is rather more than twice 

 as large as that of I. Cumingii. In consequence of this 

 greater size, I dissected, with the utmost care, the one 

 specimen which was excellently preserved in spirits, and 

 found every part, with a few exceptions, so exactly the 

 same as in the male of I. Cumingii, only larger and more 

 conspicuous, that it will be sufficient to indicate the few 

 points of difference. 



The most conspicuous difference is, that the oblique 

 fold separating the thorax and peduncle is more plainly 

 developed, projecting at the point corresponding to h in 

 fig. 1, PL V, Troths of an inch ; in the middle the fold is 

 notched ; it can be traced more easily than in I. Cumingii, 

 running beneath and parallel to the basal edge of the 

 mouth, to the ventral margin of the body. In the mouth 

 there is hardly any difference ; the maxillae, however, 

 have two notches even plainer than in the hermaphrodite 

 /. quadrivahis, or than in the male I. Cumingii, but the 

 depth of such notches is always a variable character ; 

 there are also more spines on the edge in the male of the 

 present species, than in /. Cumingii. Both mandibles 

 and maxillae in the male I. quadrivalvis, are larger than in 

 the male I. Cumingii, to a greater degree than the larger 

 proportional size of the body in the former will account 

 for ; and this, likewise, is the case with these same organs 

 in the hermaphrodite I. quadrivalvis compared with the 

 female I. Cumingii. The tubular olfactory orifices are 

 situated in the same peculiar position as in the herma- 

 phrodite, and as in both sexes of L Cumingii : they are 

 3^th of an inch in diameter, and about as thick as one of 

 the lower segments in the rami of the sixth cirrus. 



The thorax, as in the male of I. Cumingii, is quite 



