PHILOSOPHY OF ZOOLOGY. 



Fishes with the sexes distinct, and with internal impreg- 

 nation. In this division are included the chondropterygii, 

 and likewise a few osseous fishes. In the males of this di- 

 vision, at least in those of the chondropterygii, the testes 

 are two in number, flat, and of great extent. Each is divided 

 into two portions ; the first resembles the soft milt of ovi- 

 parous fishes, and the second consists of small spherical glan- 

 dular bodies. From these an epididymis is produced, 

 chiefly composed of convoluted tubes, which terminate in a 

 vas deferens ; the under part of which is greatly dilated, 

 and forms, as in birds, a considerable receptacle, or vesicula 

 seminalis. Contiguous to the outer side of the dilated end 

 of the vas deferens, there is a bag of considerable size, filled 

 with a green liquor, which is discharged into the same fun- 

 nel with the semen, and probably at the same time with it. 

 By some, this is considered as a vesicula seminalis, while, 

 by others, it is regarded as supplying the place of a pro- 

 state gland. The funnel through which the seminal fluid 

 is poured, opens near the cloaca, and, in some cases, is a 

 little produced externally. 



In the males of the chondropterygii, there are certain 

 organs situated near the anus, consisting of bone, cartilage, 

 and muscles. These were long regarded as the external 

 organs of reproduction. But RONDELETIUS was of opinion 

 that these were only accessory organs, and enabled the 

 males to retain the females more closely during coition. 

 The celebrated ichthyologist BLOCK, from dissections, ar- 

 rived at the same conclusion. They are termed claspers. 



The male organs of the sharks and rays, are such as we 

 have now described ; but few accurate observations have 

 been made on the male organs of these ovoviviparous fishes, 

 which belong to the branchiostegous and osseous tribes, such 

 as the syngathus, blennius, and muraena. 



