SEXUAL OKGANS OF THE CHONDEOPTERYGMI. 669 



the egg become encased. The egg when complete has somewhat the 

 shape of a pillow-case, with the four corners lengthened out into long 

 tendril-like cords (fig. 326), whereby the egg is entangled amongst the 

 sea-weed at the bottom of the ocean. A brittle egg-shell would soon be 

 destroyed by the beating of the waves; hence the necessity for the 

 corneous nature of the envelope ; and yet, how is the feeble embryo to 

 escape from such a tough and leather-like cradle ? This likewise has 

 been provided for : the egg remains permanently open at one extremity, 

 or, to carry out our humble simile, one end of the pillow-case is left 

 unsewn; the slightest pressure from within, therefore, separates the 

 valvular lips of the opening ; and no sooner has the little Shark thus 

 extricated itself from its confinement than the two sides close again so 

 accurately that the fissure is not at all perceptible *. 



(1853.) The sexual organs of the male Chondropterygii are very re- 

 markable, and their real character is not properly understood. The 

 testicle (fig. 327, n) is large, and occupies the same position as the ovary 

 of the female ; but the singularity of this testis consists in its being 

 made up of two portions, one of which has an excretory duct, while the 

 other, although equally bulky, has none. 



(1854.) The former portion, when minutely examined, is composed 

 of an immense assemblage of flexuous secerning vessels, that pour their 

 secretion into a long and tortuous vas deferens (o), which, after running 

 in a zigzag course nearly the whole length of the abdomen, dilates into 

 a capacious reservoir of semen (p\ and ultimately terminates with its 

 fellow of the opposite side in a conical fleshy organ (fc), which may be 

 presumed to answer the purpose of an intromittent apparatus. 



(1855.) The second portion of the testis appears to consist of globular 

 bodies having no excretory duct whatever ; and it is not impossible that 

 this is an organ analogous to the testis of the Lamprey, and that its 

 secretion escapes into the abdominal cavity, to be expelled through two 

 orifices (s s) situated on each side of the anus, whereby a free communi- 

 cation exists between the interior of the peritoneal sac and the external 

 surface of the body. 



(1856.) In these highly-organized genera impregnation takes place 

 internally, and the male is furnished with two strong prehensile organs 

 called clasjpers (I), by means of which he seizes and securely holds the 

 female during copulation. 



* According to Cuvier, in those Sharks which are viviparous (that is, whose young 

 are hatched in the oviduct prior to their expulsion) this egg-shell is never formed, and 

 the investments of the foetus remain permanently membranous (loc. tit. p. 397). 



