Mr. A. Hancock on the Anatomy of Antiopa Spinolse. 35 



must be considered the vagina, is continued on to the orifice 

 opening externally between and above the male and female out- 

 lets. This vagina, or copulatory passage, we thus see, com- 

 municates with the oviduct as well as with the spermatheca very 

 much in the same manner as in Eolis. 



The spermatheca (tig. Q>j & fig. 7 g), a rather small membranous 

 sac of a globular form, lies half-buried in a fissure which divides 

 the two portions of the mucus-gland, and gives off from its 

 anterior margin the duct above alluded to. The mucus-gland is 

 a large, pyriform mass, a little flattened, lying against the 

 wall of the visceral cavity immediately behind the penis. It is 

 composed of two parts, one (fig. 6 g) semi-pellucid and without 

 colour, the other (h) of an opake fleshy hue. These parts are 

 formed of a convoluted tube, very large and not much folded in 

 the former, in the latter minute and intricately rolled up. They 

 both open directly into the female channel (i). This gland se- 

 cretes the substance forming the gelatinous mucus-like envelope 

 that covers the eggs. 



Thus it is evident that the generative apparatus of Antiopa is 

 very complete, exhibiting the same union of male, female and 

 androgynous parts as observed in Eolis. Here, as in that genus, 

 the spermatheca will receive the semen of another individual shed 

 during coitus, and will discharge it, when required, into the 

 oviduct; and as the latter is in connexion with the testis, it 

 would appear probable that, in failure of copulation, the ova may 

 be also fertilized by a species of self-impregnation. In Antiopa 

 Spinola there is only one spermatheca, though perhaps the 

 second dilated portion of the oviduct may act as an accessory 

 receptacle. From this deficiency and from the general arrange- 

 ment of the androgynous apparatus, the generative organs of 

 this animal more closely resemble those of Eolis than of Doris ; 

 though the form of the mucus-gland approximates nearer to that 

 of the latter. 



M. Blanchard has entirely misunderstood these organs; his 

 figure of them is most imperfect, and proves that he has failed 

 to make out the various parts. He has never seen the sperma- 

 theca, nor the junction of the testis with the oviduct, and of 

 course knows nothing of the union of the latter with the sper- 

 matheca ; he calls the mucus-gland, in connexion with the female 

 channel, the testis, and the testis the vas deferens. 



After this account of the anatomy of Antiopa Spinolce, there 

 can be little hesitation about its true position in the classification. 

 It must undoubtedly be placed with the Eolididse, as proved by its 

 digestive apparatus, the hepatic canals being arranged after the 

 type of those of Eolis ; while the internal network of hepatic 

 tubes, the backward and dorsal position of the anus, the character 



3* 



