NOTES ON THE ANATOMY OP DINOPHILUS. 131 



giyen by M'lntosh (9) of D. vorticoides it appears probable tbat the 

 entire male generative apparatus of this latter species closely re- 

 sembles that of D. tseniatus. 



So far as I am aware^ copulation bas not hitberto been actually 

 proved to take place in any species of Dinopliilus* Tbe proof tbat 

 sucb a process takes place in D. tseniatus is very readily obtained 

 by merely placing a considerable number of individuals of both sexes 

 in a small quantity of sea-water, as in a watch-glass. Under these 

 circumstances, it is noticed, even a very short time after the animals 

 have been placed together, that here and there a male is attached, 

 by means of its penis, to the body of a female. In these cases, the 

 terminal, conical portion of the penis is protruded through the gene- 

 rative pore, and is passed into the skin of the female ; spermatozoa 

 are then seen to have passed from the vesiculse seminales, through 

 the skin of the female, and to be accumulating themselves into a 

 mass immediately beneath the perforation made by the penis. 



There seems to be no localisation of the spot at which spermatozoa 

 can be introduced into the female. The penis can obviously be 

 inserted into the skin at any point, as is shown by the fact that, in 

 the cases actually observed, the point selected was sometimes in the 

 region of the neck, in other cases far back in the body of the female, 

 and in other cases near the middle of the body. 



The act of copulation has no relation to the maturity of the ova 

 of the female, nor is it prevented by the fact that the female has 

 already received an ample supply of spermatozoa by a preceding 

 operation. It was extremely difficult to discover any female, in which 

 ovaries were recognisably developed, which did not contain large 

 numbers of spermatozoa in its body-cavity. These were observed in 

 almost any part of the body of the animal, their position being pro- 

 bably partly dependent on the manner in which fertilization had been 

 previously effected. The spermatozoa show, however, a great tendency 

 to accumulate into a large compact mass, situated in a space on the 

 ventral side of the stomach {v. fig. 14, and description of the female 

 generative organs). In some cases it was observed that the female 

 was receiving spermatozoa simultaneously from two males, in others 

 that while, for instance, fertilization was being effected near the 

 posterior end of the body, a great mass of spermatozoa (obviously 

 obtained on a previous occasion) was visible at the anterior end of 

 the body. In many cases the females were enormously distended with 

 spermatozoa, which could hardly have been all received at one time. 



The common occurrence of great numbers of spermatozoa in the 

 body of the supposed female might suggest that D. tseviatus was 

 hermaphrodite. Such a supposition is rendered sufficiently improbable 

 * Korscbelt (6) lias probably seen somctliiiig of tliis process in D. gyrociliatus. 



