288 



LECTDRE XII. 



capsule or ' tunica albuginea,' and a peritoneal covering : the capsule 

 sends many ' septa' into the testes ; and the lobes thus formed consist 

 chiefly of the tubuli testis, and their expanded cell- 

 like extremities, filled with the spermatozoa : the 

 convolutions of the ' tubuli' are plainly discernible 

 in the portion of the testis of the great Basking 

 Shark preserved in No. 2396. A. Numerous ' vasa 

 efferentia' convey the ' semen' to the beginning of 

 the ' vas deferens'* which forms a large 'epididymis' 

 (ib. b) by its manifold convolutions. These gradu- 

 ally decrease as the duct (e) approaches the cloaca, 

 when it becomes straight, and expands into an 

 elongated reservoir (ib. f), the mucous surface 

 of which is commonly increased by numerous trans- 

 verse plicEe (Selache.) Behind the termination of 

 the rectum the ' vasa deferentia' suddenly diminish, 

 approximate, communicate with the ureters, and 

 terminate upon the rudimental cloacal penis (ib. g, k, 

 and prep. 2396.). 



The claspers (ib. m) are present in the Chimse- 

 roid Fishes as well as in the Plagiostomes. They 

 project backwards as appendages to the bases of 

 the anal fins, and are sometimes bent inwards at their free ex- 

 tremities. Near this part may be discerned a fissure which is 

 the outlet of a blind sac extending forwards from the base of the 

 clasper beneath the muscles and skin, at the sides of the cloaca. 

 The inner surface of the cavity is smooth, and lubricated by a fluid 

 mucus : the attached vascular surface is richly supplied with ves- 

 sels, especially with veins : in the Rays a glandular body adds its 

 secretion to that of the surface of the cavity. 



N.^ 



Male Organs, 

 left side: Spinax. 



FEMALE ORGANS. 



The gradations of structure of the female organs correspond very 

 closely with those of the male. In the young Lamprey the ovarium 

 is a simple longitudinal membranous plate, suspended by a fold of 

 the peritoneum (mesoarium) along the under part of the vertebral 

 column : it increases in breadth and thickness as the ova are deve- 

 loped in it, and still more so in length, being accommodated to its 

 locality by numerous folds {fig. 74. c). But no superadditions are 

 made to this primitive structure : the ova {d) escape by rupture of their 



