592 



ANATOMY OF VERTEBRATES. 



spirals about the body, fig. 409. The spermatozoa of the 

 Salamander and Newt have a similar form and disposition, and the 

 coils of the reflected tail present the appearance of a crenate 

 fringe or ridge, as in fig. 410. The fully-developed spermatozoa 

 of Pelobates fuscus have a long spirally disposed body, gradually 

 attenuating into the filamentary appendage, fig. 411; the total 

 length is about -$ of a line : the looser anterior end has a constant 

 vibratile motion. 



In the Frog, fig. 412, the body of the spermatozoon is long, 

 cylindrical and straight, and is terminated by a straight capillary 



411 



412 



413 



414 



Spermatozoa of Pelobates 

 fuscus. 



Spermatozoon of 

 Eana tcmporaria. 



Spermatozoa of Lacertn 

 agilis. 



Sperm-cell, a, with 

 four spermatoa, b, 

 and their contained 

 spermatozoa, Tes- 

 tudo grated, cccvu. 



appendage. In the Coluber natrix the body of the spermatozoon 

 is pointed anteriorly : in Lizards it is shorter and more obtuse, 

 fig. 413. The spermatoa rarely exceed eight in number in the 

 sperm-cell, from which they usually escape prior to the full 

 developement and extrication of the spermatozoa. The same 

 is the case also in Testudo grceca : but here the sperm-cell, 

 fig. 414, , remains longer than in Lizards and Snakes, and 

 spermatoa, ib. b, with developed spermatozoa, may be observed 

 within it. 



112. Ovulation in Osseous Fishes and Botrachians.- -In 

 Cyclostomous and Teleostomous Fishes, and in Batrachians, the 

 ova are developed almost simultaneously at each breeding season : 

 whilst in Chimasroid and Plagiostomous Fishes, as in scaled 



o 



Reptiles, the ova are successively developed, or come to perfection 

 at longer or shorter intervals. In Osseous Fishes, however, 

 besides the ova of the present season, there are the germs of 

 those of the next, often studding the ovisacs of the former. In 

 the ovary of the Frog, before pairing-time, three sets of ova are 



