236 SCALPELLUM VULGARE, 



there were vast numbers of cells, sometimes cohering in 

 sheets, about To^hs of an inch in diameter, and having 

 darkish granular centres ; these I believe to be the testes, 

 for in a specimen presently to be mentioned, in which 

 the vesicula seminalis was gorged with spermatozoa, I 

 found adhering to its outside, a mass of cells of exactly 

 the same diameter, but now empty and transparent instead 

 of having brownish centres. Lastly, in several other 

 specimens, at the very bottom of the sack -formed animal, 

 there was a brownish, pear-shaped bag, of different sizes 

 in different individuals, and occasionally broader even than 

 the thorax. This bag contained either pulpy matter, or 

 a great mass of spermatozoa. Before being disturbed, 

 these spermatozoa lay parallel to each other in flocks, and 

 they yielded to the needle in a peculiar manner, so that I 

 found (having had experience with these bodies in living 

 Cirripedia) I could almost tell before examination under 

 the compound microscope, wmether or not I should see 

 spermatozoa. Many had distinct heads,* which were two 

 or three times as broad as the filamentary bodies ; the 

 latter when placed between glass were the o^th of an 

 inch in diameter. I compared these spermatozoa with 

 others taken out of the vesiculae seminales of the individual 

 hermaphrodite S. vulgare, to which the parasite was 

 attached, and could not perceive the slightest difference 

 in them. The brownish pear-shaped bag, or vesicula 

 seminalis, the coat of which seems fibrous, could some- 

 times be distinctly traced, sending a chord or prolonga- 

 tion far up the thorax : at the end of the abdominal lobe, 

 no doubt there is an orifice ; and this, I believe, I once 

 distinguished. Owing to this chord, the bag often 



* I do not understand the development of the spermatozoa in Cirripedia : 

 in a recent Chthamalus and Balanus, I found the greater number had a little 

 filament in front of the head or nodular enlargement, which latter varied in 

 size and in shape from globular to that of a spindle. The filament before the 

 head, also, varied in proportional length; ;t did not project in exactly the same 

 straight line with the hinder part, and some of the spermatozoa were entirely 

 without this filament in front; — such is the case with the spermatozoa here 

 described. 



