198 IBLA CUMINGII, 



Concluding Remarks. — That these animals are true 

 Cirripedes, though having so different an external appear- 

 ance from others of the class, admits of not the least 

 doubt. The prehensile antennae, enveloped in cement and 

 including the two cement -ducts, would have been amply 

 sufficient, without other parts — for instance, the mouth, by 

 itself perfectly characteristic with each organ, together with 

 the whole alimentary canal, constructed on the normal plan, 

 — to have proved that they were Cirripedia. Under the 

 head of the closely-allied Ibla quadrivalvis, we shall, more- 

 over, see that the males are developed from larvae, having 

 every point of structure — the peculiar quasi-bivalve shell, 

 the two compound eyes, the six natatory legs, &c, — 

 characteristic of the Order. But in some respects, the 

 males are in an embryonic condition, though unquestion- 

 ably mature, as shown by the spermatozoa ; — thus, in the 

 thorax and mouth opening throughout their whole width 

 into the cavity of the peduncle, that is, homologically into 

 the anterior part of the head, and in the viscera being there 

 lodged instead of in the thorax and prosoma, there is a 

 manifest resemblance to the larva in its last stage of develop- 

 ment : the absence of a probosciformed penis, the spine- 

 less peduncle, the food being obtained without the aid of 

 cirri, and the length of the rectum, are likewise embryonic 

 characters. Not only are these males, as just remarked, 

 Cirripedia; but they manifestly belong to the Pedunculated 

 Family. If a specimen had been brought to me to class, 

 without relation to its sexual characters, I should have 

 placed it, without any hesitation, next to the genus Ibla ; 

 if the mouth alone had been brought, I should assuredly 

 have placed it actually in the genus Ibla : for let it be 

 observed how nearly all the parts resemble those of Ibla 

 Cumingii, excepting only in size and in being less hairy. 

 The tropin are arranged in the same peculiar position 

 as in the female ; the labrum is largely bullate, without 

 teeth on the crest ; the palpi, though relatively smaller, 

 are of the same shape ; so are the mandibles ; the maxillae 

 are more rounded and less prominent, but have the same 



