METAMORPHOSES OF CIRRIPEDES. 109 



Zoea, or larva of certain Poclophthalrnia. Situated under 

 this posterior prolongation of the carapace, there is a swelling 

 (n, with long hairs on both sides), which apparently lies on 

 the dorsal surface of the spinose and forked abdomen ; 

 here, when the larva is compressed, the cellular and oily 

 contents of the body burst forth ; and I suspect that this 

 swelling is the anus, for it is known from the researches 

 of Ratlike,* that the anus in the higher Crustaceans opens 

 during the earliest periods dorsally. 



Larva, second stage. — I have given, from Burmeister,f 

 a lateral view (PL 30, fig. 1) of the one single specimen, ever 

 observed of a larva in this stage, belonging, as is supposed, to 

 the genus Lepas. The carapace has now greatly altered its 

 character. The two fleshy projections, as so called by Bur- 

 meister, by which the larva adhered to the sea-weed, were 

 supposed by this author to include the great prehensile an- 

 tennae of the pupa • from my observations, already alluded 

 to, on the two projections (PI. 24, fig. 17) in the closely ana- 

 logous egg-like larva, in the second stage, of Cryptophialus, 

 by which it also adheres, I have not the least doubt that this 

 is the case. The small, internal, and anterior pairs of an- 

 tennas, are, as it would appear, now aborted. The eye, accord- 

 ing to Burmeister, has commenced becoming double; but the 

 two approximate eyes are not as yet compound. The mouth 

 is probosciformed (m), and does not differ much from its 

 condition in the first stage ; no gnathites were observed by 

 Burmeister, and they could not be expected to be present, 

 for they are not found even in the pupa. The mouth, which 

 in the larva in the first stage differs in different genera, in 

 being more or less advanced forward, here stands some way 

 anteriorly to the natatory legs, as in the pupal condition. 

 The first pair of legs is uniramous, and the two other pairs 

 biramous ; this fact, together with the number of the legs 

 in this second stage being still three, and their structure being 

 not very different, leaves little doubt on my mind that we 

 here have the same three pairs as during the first stage. 

 The abdomen has become much shortened, but still space 

 is left for the development, in the pupa, of the three pos- 



* 'Annales des Scienc. Nat.,' torn, xx, p. 451. 



f 'Beitrage zur Naturgeschichte der Rankenfiisser,' tab. 1, figs. 3, 4. 



