COMPLEMENTAL MALE. 211 



four, I believe five, larvae, which in every main point of 

 structure resembled the larvae of other pedunculated 

 Cirripedes. From the peculiar form of their prehensile 

 antennae, differing in no respect, except in the propor- 

 tional lengths of the segments, from the same organ in 

 the male /. Currdngii^ I can feel no doubt that these were 

 the larvae of the male I. quadrivalvis ; — for a moment's 

 reflection will show how excessively improbable it is, that 

 several larvae of some other Cirripede, and that a Cirri- 

 pede intimately allied to the parasitic male Ibla, should 

 have forced themselves, without any apparent object, into 

 the sack of the hermaphrodite Ibla. The larvae, though 

 not yet attached, were on the point of attachment, 

 so that the single eye of the mature animal could be 

 distinctly seen, lying near to the two great compound eyes 

 of the larva. We have also just seen, that one male quite 

 recently here had undergone its metamorphosis. The 

 larvae are T f§oths of an inch in length, and rather more than 

 -^oths in width in the widest part : they are boat-shaped, 

 the dorsal edge forming the keel of the boat ; the ante- 

 rior end is only a little blunter than the posterior end ; 

 the quasi-bivalve carapace is smooth. All the essential 

 points of structure in the larvae of other Cirripedes at 

 this stage, could be distinctly here seen, — such as the 

 two compound eyes, with the apodemes to which they 

 are attached, and the two oblong sternal plates whence 

 the apodemes spring, — the adductor muscle, — the six 

 natatory legs, with long plumose spines, — the abdomen, 

 with its three small segments and the caudal appendages, 

 — the prehensile antennae already described, — and, lastly, 

 the two little (auditory ?) sacks at the an tero- sternal edges 

 of the carapace, but not so near the anterior extremity as 

 in Lepas. The four or five larvae, after having undergone 

 in the open sea the several preparatory metamorphoses 

 common to the class, must have voluntarily entered the 

 sack of the hermaphrodite : ultimately would they, on 

 finding two males already attached there, have retired, 

 and sought another individual less well provided ; or 



