580 ORDER ABDOMINALIA. 



tion for the whole body (fig. 17), whereas the two anterior 

 horns have approached each other on the future ventral sur- 

 face, and have increased considerably in length and thickness, 

 and contain within them the prehensile antennae, which can 

 be externally seen, and which I dissected out of these horn- 

 like cases. The oval part of the egg-like larva (for I hardly 

 know what to call it) is now very slightly shrunk, being hardly 

 more than ^gths of an inch in length. At this stage, these 

 bodies adhere by the tips of their anterior horns, containing 

 the antennae in process of formation, to the inner tunic of 

 the sack, and likewise in little groups one to another : as the 

 included prehensile antennas ultimately become attached by 

 cement (proceeding, no doubt, as usual, from a modified 

 portion of the ovarian tubes), it seems probable that some 

 cement may at this early period be excreted, but I could 

 not make out the exact means of attachment. The egg- 

 like larvae are, also, aggregated round the tapering curled 

 dorsal appendages of the second and third segments of the 

 body, and it is possible that at this, or at an earlier period, 

 these appendages may act like the ovigerous fraena in the 

 Lepadidae, and serve to retain the egg-like larvae within the 

 sack. 



We come now to the last larval, or pupal condition, 

 before the final metamorphosis into the mature animal; the 

 changes above described have been, at least to a great 

 degree, if not absolutely gradual; but the pupa suddenly 

 appears perfectly developed, from the moulting of the last- 

 described horned, egg-like larva. It is now a free animal 

 crawling about the sack of its female parent. It has increased 

 a little in length, as compared with the oval part of the egg- 

 like larva in its second stage, namely, from a little above 

 ^ths to froths of an inch: from the position of the prehensile 

 antennae in the two states, I have no doubt that this increase 

 of size is entirely due to the anterior part of the pupa being 

 doubled up whilst within the egg-like larval envelope. The 

 pupa in shape (fig. 18) somewhat resembles a coffin, and is 

 far less laterally compressed than other pupae, and hence can 

 easily be placed either on its dorsal or ventral surface. The 

 prehensile antennae are of large size : when the animal was 

 alive, they were concealed under and partially included within, 



