210 IBLA QUADRIVALVIS, 



make out. The anus was much plainer than in the 

 male of I. Cumingii. I saw the eye distinctly. I could 

 not distinguish the orifices of the acoustic (?) sacks ; and 

 I think I should have seen them, if they had existed. 



Prehensile Antenna. — I examined these in the larvae 

 presently to be mentioned, and therefore they were in 

 better condition than in the mature animal when 

 cemented. Their total length, measured along the out- 

 side, from the basal articulation to the end of the disc, is 

 sloths or ^ths of an inch — that is, one third longer than 

 in I. Cumingii ; whilst the hoof-like disc itself is ^ths, or 

 only g^oth of an inch longer than this same part in 

 I. Cumingii : the apex of the disc is downy, or bears 

 some excessively minute spines. The ultimate segment 

 has its end irregularly rounded, with the spines obscurely 

 divided into two groups, the outer group consisting of two 

 or three longer and thinner spines, and the inner group of, 

 as I believe, five rather shorter spines : the longer spines 

 equal in length the whole ultimate segment. I could not 

 perceive that they were plumose, as in many other genera. 

 A single, rather thicker and long spine, pointing back- 

 wards, is attached to the under side of the disc, nearly 

 opposite to the point where the ultimate segment is arti- 

 culated on the upper convex surface. Another single, 

 curved spine is attached on the outer side of the basal 

 segment, near its distal end. 



Development of the Male. — In the specimen before al- 

 luded to, which included two males, one of these was only 

 the i&ths of an inch in length, and therefore between one 

 fifth and one sixth of the size of the mature male. It had, 

 probably, undergone only one exuviation since its meta- 

 morphosis, for the larva is nearly as long, namely, Tilths 

 of an inch. In this young male, the mouth formed one 

 third of the entire length : it was attached, not as in every 

 other case to the sack of the hermaphrodite, but low 

 down to the peduncle of the other male. 



In the sack with these two males, there were certainly 



