104 BALANID.E. 



specimens most kindly sent me by Mr. Bate) of the larva of 

 Chthamalus stellatus (fig. 10), in its first stage, but after 

 moulting o?ice. It should be observed that Mr. Bate has 

 given a drawing of the larva of this latter cirripede, in the 

 first stage, before moulting ; and it does not differ essentially 

 from that just referred to (fig. 9), of B. balanoides, but is 

 rather more fully developed. These drawings suffice to show 

 the character of the larvae in the first stage, both before and 

 after the first moult, and even after the second moult, 

 throughout the Order of Thoracica. The larvae some- 

 times undergo their first moult within the sack of their 

 parent, as I have been informed by Mr. Bate, and as I have 

 observed in Coronula. 



I will now make a few remarks on these larva? in the 

 first stage, before and after the first moult, supplemental to 

 those in my former volume. Their shape is oval, and the 

 whole dorsal surface is evidently covered by a carapace. It 

 is remarkable that the body exhibits no distinct articula- 

 tions; those given by Goodsir* being certainly erroneous. 

 Commencing at the anterior extremity, the eye varies con- 

 siderably in the state of its development ; in Platylepas de- 

 corata it is nearly circular, and in most of the specimens 

 very distinct; whereas in the allied Coronula balcenaris, 

 before the first moult, it is very imperfect, but afterwards 

 square and of considerable size. In Balanus elongatus, in 

 the immature larva? dissected out of the egg, the cellular 

 matter which was in process of conversion into the eye, 

 formed a transverse band, obscurely divided into two por- 

 tions, and this seems to indicate that the single eye is in 

 fact formed by the confluence of two eyes. In Scaljoellum vul- 

 gare, this heart-shaped eye lies between a V-shaped muscle, 

 the nature of which I cannot understand, and which has not 

 been represented in (PI. 29, fig. 8, a). I need only further 

 add, that in Chthamalus stellatus, after the first moult, the 

 eye exhibits, in specimens sent me by Mr. Bate, some ap- 

 pearance of tending to become double. 



Arising posteriorly to the eye, we see, in Scaljjellam vul- 

 garis a pair of minute curved horns (£'), directed back- 



* 'Edinburgh New Philosophical Journal,' July, 1843, PL 3, 4. 



