I have given, from Burmeister,[58] 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 Burmeister, by which the larva adhered to the sea-weed, were supposed by this author to include the great prehensile antennæ of the pupa; from my observations, already alluded to, on the two projections (Pl. 24, fig. 17) in the closely analogous 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 antennæ, are, as it would appear, now aborted. The eye, according 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 posterior pairs of legs. I may here remark that in the pupa the anterior natatory legs have become, like the others, biramous; but yet, as it were for the purpose of showing their metamorphosis from the uniramous legs of the earlier stages, they have their bristles arranged rather differently from those on the succeeding five pairs of legs. [58] 'Beiträge zur Naturgeschichte der Rankenfüsser,' tab. 1, figs. 3, 4. _Larva in the Last or Pupal Stage._