Lastly, behind the natatory legs, on the ventral surface, (Pl. 29, figs. 8, 9, _i_), the body is much produced, and terminates in a horny fork, which, after the first moult (fig. 10, _i_), becomes much elongated. Anteriorly to this fork, on the ventral surface, there is another fork (_l_), and again above this I could distinguish, in _Chthamalus stellatus_, after the first moult, another fork (_m_), or at least a pair of short thick spines. From the structure of the forked abdomen in the known larvæ of the Podophthalmia, I presume that this portion of the body is the abdomen of the young Cirripede, but it is not at all plainly articulated. After the first moult, the posterior end of the carapace (_h_), which is always pointed, becomes much elongated and serrated on both sides;[56] reminding one of the structure of the carapace of the so-called Zoea, or larva of certain Podophthalmia. 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 Rathke,[57] that the anus in the higher Crustaceans opens during the earliest periods dorsally. [56] I suspect that the account given by Goodsir ('Edinburgh New Phil. Journal,' 1848) of the posterior points of the carapace and abdomen in the larva of a Balanus, is not quite accurate. [57] 'Annales des Scienc. Nat.,' tom. xx, p. 451. _Larva, Second Stage._