THE URINOGENITAL ORGANS OF VERTEBRATES. 153 



Professor Turner (Journal of Anat. and PJiys. Vol. VIII.) failed 

 to find either oviduct or vas deferens, but found a pair of large 

 open abdominal pores, which he believes serve to carry away 

 the generative products of both sexes. Whether the so-called 

 abdominal pores of Selachians usually end blindly as in Scyl- 

 lium, or, as is commonly stated, open into the body-cavity, 

 there can be no question that they are homologous with true 

 abdominal powers. 



The blind pockets of Scyllium appear very much like the 

 remains of primitive involutions from the exterior, which might 

 easily be supposed to have formed the external opening of a 

 pair of segmental organs, and this is probably the true meaning 

 of abdominal pores. The presence of abdominal pores in all 

 Ganoids in addition to true genital ducts and of these pockets 

 or abdominal pores in Selachians, which are almost certainly 

 homologous with the abdominal pores of Ganoids and Cyclo- 

 stomes, and also occur in addition to true Miillerian ducts, speak 

 strongly against the view that the abdominal pores have any 

 relation to Miillerian ducts. Probably therefore the abdominal 

 pores of the Cyclostomous fishes (which seem to be of the same 

 character as other abdominal pores) are not to be looked on as 

 rudimentary Miillerian ducts. 



We next come to the question which I reserved while speak- 

 ing of the kidneys of Osseous fishes, as to the meaning of their 

 genital ducts. 



In the female Salmon and the male and female Eel, the een- 



o 



erative products are carried to the exterior by abdominal pores, 

 and there are no true generative ducts. In the case of most 

 other Osseous fish there are true generative ducts which are 

 continuous with the investment of the generative organs 1 and 



enable me to determine for certain the presence or absence of these pores. Mr Bridge, 

 of Trinity College, has, however, since then commenced a series of investigations on 

 this point, and informs me that these pores are certainly absent in Scyllium as well as 

 in other genera. 



1 The description of the attachment of the vas deferens to the testis in the Carp 

 given by Vogt and Fappenheim (Ann. Sacn. Nat. 1859) does not agree with what I 

 found in the Perch (Perca fluvialis). The walls of the duct are in the Perch con- 

 tinuous with the investment of the testis, and the gland of the testis occupies, as it 

 were, the greater part of the duct ; there is, however, a distinct cavity corresponding 

 to what Vogt and P. call the duct, near the border of attachment of the testis into 



