242 SCALPELLUM VULGARE, 



furnished with muscles, are obviously, as already re- 

 marked, of no use for prehension ; these parts serve, 

 probably, to defend the little creature, when its eye 

 announces the passing shadow of some enemy, and for 

 this purpose they are well adapted from the extreme 

 sharpness of the spines. The thorax, into which I traced 

 the vesicula seminalis, no doubt also serves for the emis- 

 sion and first direction of the spermatozoa ; and hence, 

 perhaps, its singularly extensible structure. I have already 

 remarked, that in specimens preserved in spirits, the 

 thorax is often largely protruded, and bent down at 

 right angles to the orifice. I presume this is caused by 

 endosmose ; nevertheless it deserves notice, that it was 

 in these protruded specimens that the vesicula seminalis 

 was most conspicuously gorged with spermatozoa. I 

 suspect the longitudinal and transverse muscles lining the 

 upper part of the outer integuments of the whole animal, 

 can be of little use to the creature, without it be to aid 

 in the protrusion of the thorax, and perhaps in the violent 

 expulsion of the spermatozoa, thus causing them to reach 

 the ovigerous lamellae within ihe sack of the hermaphro- 

 dite. It is also probable, that the action of the cirri of 

 the hermaphrodite, would tend to draw inwards the sper- 

 matozoa in the right direction. In one specimen, the 

 spermatozoa in the hermaphrodite and in the male were 

 mature at the same time; in another this was not the 

 case ; and as the males, apparently, become attached at 

 all periods of the year, this want of coincidence in maturity 

 must often occur. Can the males retain their sperma- 

 tozoa, till told by some instinct, that the ova in the sack 

 of the often fecundated hermaphrodite are ready for im- 

 pregnation ; or are the spermatozoa sometimes wasted, 

 as must annually happen with such incalculable quantities 

 of the pollen of many dioecious plants ? 



This little Cirripede is, in many respects, in a partially 

 embryonic condition. There is no separation between 

 the capitulum and peduncle j there is no mouth ; and the 

 thorax, throughout its whole width, opens into the anterior 



