/>90 



ANATOMY OF VERTEBRATES. 



Fishes the spermatozoa resemble those of the Perch, fig. 400 : but 

 in some, e. g. the Loach, there is a small swelling at the insertion 

 of the appendage, as in fig. 401. In a few the ' body ' is scarcely 

 indicated, e. g. in the river Lamprey, fig. 402 : in the Petromyzon 

 marinus the body expands into an egg-shape. 



400 401 402 



Spermatozoa of Perca 

 fliiviatilis. cccvi. 



Spermatozoa of Cobitis 

 fossilis. cccvi. 



Spermatozoon of Petromyzon 

 fluviatilis. cccvi. 



The spermatozoa in the Plagiostomes are very long, with an 

 anterior cylindrical body. This is proportionally shortest in 

 Chimcera monstrosa, and is disposed in three spiral coils : in 

 Scyllium canicula it is about half the length of the spermatozoon, 



403 



404 



405 



A. Spermatozoa of 

 Scymnus nicceensis. cccvi. 



B 



B. Spermatozoon of 

 Torpedo Narce. cccvi. 



Spermatozoa within the 

 sperm-cell (Torpedo Narce). 

 CCCVI. 



is straight, and tapers at both ends : in Scymnus nic&ensis, fig. 

 403, it is spirally disposed. In Spinax acanthias, the Rays and 

 Torpedos, fig. 404, the spiral coils are rather closer, usually four 

 in number: in Raia oxyrhynclius the coils are more numerous, 

 but only affect the anterior half of the body. 



In the Plagiostomes the spermatoa appear as one or more nuclei 

 within the sperm-cell, like those in fig. 399, b : but they are not, 

 as in Osseous Fishes, excluded in that state. * In each spermatoon 



1 cccvi. vol. iv. p. 484. 



