Mr. Lubbock on two new Subgenera of Calanidse. 207 



AUman, has its external ovary on the back, and in the Daphnidce 

 the receptacle for the eggs, which corresponds in function, is 

 always situated dorsally, whereas the spermatic tube is attached 

 on the under surface close to the vulva, as would appear evident ; 

 for if it was not so, how could the spermatozoa reach the eggs ? 

 It may perhaps be said, that the glutinous matter forms a tube 

 down the side of the body, and in that way opens close to the 

 vulva ; but this does not appear to me probable, for in that case 

 the animal would lose its equilibrium ; and besides, I could see no 

 excrescence of that sort ; and if it were present, I could hardly 

 have overlooked it. Unless then we suppose that the vulva is 

 situated on the back, its position seems rather in favour of its 

 being an external ovary. From the function of the spermatic 

 tube, we should expect to find it only when the eggs were well 

 developed, but I could not see them in any one of the Jkree 

 females provided with this organ which I have examined ^jr is 

 true, however, that in the figure of the female C. hyperboreus 

 above referred to, which is provided with a spermatophore, no 

 external ovary is represented. Its size also seems almost too 

 large to admit of its having been developed in the generative 

 organs of the male. 



The shape of the organ in question, though certainly very dif- 

 ferent from that of the external ovary in the rest of the family, is 

 however the same as that which prevails in all the Caligidce. In 

 Caligus the ovaries aje attached to the body by their internal 

 angles, and in Iva by the centre ; but if we consider that of the 

 latter genus as homologous with the two of the former coalesced, 

 this difference will be removed. 



The chief obstacle to this view is the absence of eggs ; but 

 Dr. Baird, in his volume on the ' British Entomostraca,^ p. 49, 

 describing the process of laying in Chirocephalus, says, " When 

 the proper time arrives, the mother deposits these eggs loose in 

 the water, the ovary opening at the point and the eggs being 

 thrown out by a sudden jerk ;" and it seems to me possible, that, 

 either in the violent struggles which follow when any Entomo- 

 stracan is placed in spirits of wine, the eggs may have been ex- 

 pelled, or that they may have been so in the course of nature 

 shortly before they were captured. 



I have endeavoured impartially to state both sides of the 

 question, but the paucity of specimens unfortunately makes it 

 impossible to prove either, so that it must be left to some future 

 observer to decide the question*. 



* Mr. Darwin and Dr. Baird, who have both examined ray specimens 

 very carefully, agree with what 1 have said above. If it had not been for 

 their assistance my task would have been much more difficult. 



