.9j5 Mtscellaneoiis. 



specimens. The Selachian genera in which I have regularly found 

 them in sexuulk mature adult individuals are as Mlows -.—Squat ina, 

 Scifinniis, CtnfrophorKS, Spina.i-, Acant/iias, Iferdnchiis (in a speci- 

 men 10 feet long). Prist in nut, and Sci/llium. In the last geneni 

 they are very small, and for the most part also altered ; on tho 

 other hand, in St'i/mnKS and S<iitaii>vi they are exceedingly large, 

 furnished with distinct funnel-shaped apertures, into which tine 

 forceps may be conveniently introduced, and are present high up on 

 the sexual fold. In Squafina especially these organs are so numerous, 

 regularly developed, and striking even in the living animal, that it 

 is quite incomprehensible to me how they can have been hitherto 

 overlooked. The following genera are destitute of them when 

 adult — Lamnn, Mu.<t,his, Gnhns, Carchurias, and probably Sphyrna ; 

 when they disappear, or whether they occur at all in the embryo, 

 still remains to be ascertained. 



In my first communication I indicated that perhaps the seminal 

 ducts originated from the segmental funnels. This is decidedly not 

 the case ; but, on the contrarj', it seems probable, especially from 

 their behaviour in Sqnaiina, that the segmental ducts may become 

 the vasa efferentia testis ; and by a growth of the epithelium of the 

 segmental funnels the epigonal organ may perhaps be produced. 

 In favour of the supposition that the primitive renal duct becomes 

 the seminal duct we seem to have the two facts :■ — -that in large male 

 embryos only a single canal is to be found, which subsequently 

 becomes the urino-seminal duct ; and, secondly, that a tuba occurs 

 in the males of all genera of Rays and Selachia, and passes on each 

 side into a canal exactly as in the females, and this evidently can 

 be nothing but the anterior end of the primitive renal duct. The 

 middle tubal orifice of the males is very large in many genera 

 {Scijmn'is, Centrophorus, Squatinn); the canals running backwards 

 from it (representing the oviducts of the female) are very soon 

 obliterated, and cannot be traced as such to the kidneys in the 

 genera which have hitherto been investigated. In a few species, 

 only a fine cord, but without a cavity, was recognized between the 

 kidney and the hinder extremity of the male tubal canal. Careful 

 investigations of the embryos have proved, however, that the per- 

 manent urino-seminal duct of the male is not the primary primitive 

 renal duet, and that the latter disappears almost entirely in the 

 region of the kidneys, whilst, as in the females, a secondary primi- 

 tive renal duct has been developed as a urino-seminal duct. This is 

 the case also in Chimcera. In the males of this species there are 

 two isolated tul>al oi)enings which lead into a fine canal lying upon 

 the urino-seminal duct ; this corresponds in position to the oviduct 

 of the female, and can be nothing but the primary primitive renal 

 duct. By this ChimcBra approaches much more closely to the 

 Ganoids than to the Plagiostomi. 



I hope soon to be in a position to follow up my first memoir, 

 which has already been referred to and will shortly appear, on the seg- 

 mental organs of the Selachia and the relationship of the vertebrate 

 and invertebrate animals, with another on the urogenital system 

 of the Plagiostomi. — Centmlhl fur die mtd. Wisx-mch. 1874, no. 52. 

 Wiirzburg, Ort. ]. 1 874. 



