METAMORPHOSES. 11 



great elongation of the posterior point of the carapace 

 into an almost filiform, spinose point in Lepas, Concho- 

 derma, Chthamalus, and Balanus, but not according to 

 Goodsir, in one of the. species of the latter genus. The 

 posterior point, also, of the abdomen becomes developed 

 in Balanus (Goodsir) into two very long, spear-like pro- 

 cesses, serrated on their outer sides ; in Lepas and Con- 

 choderma, according to Thompson, into a single, tapering 

 spinose projection ; and in Chthamalus, as figured by Mr. 

 Bate, the posterior bifid point, as well as the depending 

 ventral fork, increase much in size. Another important 

 change, which has been particularly attended to by Mr. 

 Bate, is the appearance of spinose projections and spines 

 (some of which are thick, curved, and strongly plumose, 

 or, almost pectinated along their inner sides) on the 

 pedicels and lower segments of the shorter rami of the 

 two posterior pairs of limbs. 



The mouth in its earliest condition alone remains to 

 be described ; in 8. vulgare, it is seated on a very slight 

 prominence, in a most remarkable situation, namely, in a 

 central point between the bases of the three pairs of legs. 

 I traced by dissection the oesophagus for some little way, 

 until lost in the cellular and oily matter filling the whole 

 animal, and it was directed anteriorly, which is the 

 direction that might have been expected, from the course 

 followed by the oesophagus in the larva in the last stage, 

 and in mature Cirripedes. Mr. A. Hancock has called 

 my attention to a probosciformed projection on the under 

 side of the larva of Lepas fascicidaris, when just escaped 

 from the egg. Mr. Bate has described this same pro- 

 boscis in Balanus and Chthamalus, and states the im- 

 portant fact, that it is capable of being moved by the 

 animal ; and, lastly, I have seen it in an Australian Chtha- 

 malus, and in Ibla, of remarkable size. This proboscis, 

 which is always directed posteriorly, (like the mouth in 

 the mature animal,) certainly answers to the mouth as 

 made out by dissection in Scalpellum ; and I believe I 

 saw, as has Mr. Bate, a terminal orifice : it certainly does 



