PISCES. 



1009 



ovary is distinct from the oviduct, as in the 

 three higher classes of Vertebrata. When the 

 ovules are not developed,* the ovary ^>f the 

 Sharks forms a thick oval lamina slightly 

 notched or concave upon its inner border, sus- 

 pended upon each side of the vertebral column 

 at the very anterior extremity of the abdominal 

 cavity, from which point it is prolonged back- 

 wards for a greater or less extent. The inferior 

 and internal surface of this lamina, that by 

 which the ovaria would touch each other if 

 approximated, presents no prominences, but is 

 of a uniform milk-white colour. The posterior 

 surface of the organ has the same appearance, 



Fig. 



538. 





Viscera of female Shark, after Hunter. 



a, skin ; b, cut pectoral and pelvic arches ; c, heart ; h, 

 coecal appendage to intestine ; n, ovary ; q, oviduct ; r, ute- 

 rine portion of oviduct , s, s, termination of oviducts in clo- 

 acal cavity j t, papilla on which the ureters open. 



* Cuvier, Lesons d'Anatomie Comparee, tom.viii. 1846. 



VOL. III. 



except that upon the anterior half or two-thirds 

 of the ovary little* rounded eminences of dif- 

 ferent sizes are perceptible, the smallest of 

 which are pearl-white, while the larger are of 

 an opaque-yellow colour ; these are the ovules 

 in process of developement from the proligerous 

 stratum of the ovary, which gradually increase 

 in size as they advance towards maturity, and 

 project through the upper surface of the ovary. 

 This latter expands itself in the form of a cap- 

 sule over the ovules in such a manner that as 

 their developement increases they become de- 

 tached from each other, and separating them- 

 selves more and more become at length racemose. 

 The remainder of the ovarian lamina 

 retains its soft, milky, homogeneous ap- 

 pearance, which is very characteristic, 

 and resembles very closely one portion 

 of the testis of the male. 



In many of the viviparous Sharks, 

 that portion of the ovary only which does 

 not form eggs is met with upon one 

 (generally the left) side of the body, 

 whilst upon the opposite the organ 

 attains its full developement. 



The general disposition of the rest 

 of the generative apparatus is well shewn 

 in the accompanying figure (fig. 5;>8) of 

 the sexual organs of the female Dog-fish, 

 (Spinax acanthias, Cuv.,) taken from 

 one of the admirable drawings left by 

 John Hunter, and engraved in the Cata- 

 logue of the Hunterian Museum. 



The ovary (n) presents ovisacs in dif- 

 ferent stages of developement attached 

 by a duplicature of peritoneum to the 

 side of the spine, immediately below the 

 liver and oesophagus. The anterior orifi- 

 ces of the oviducts (</,<?) are situated 

 close together above the liver ; their 

 coats, which are at first thin and mem- 

 branous, gradually increase in thickness, 

 and about four inches from the orifice 

 become suddenly thickened by the addi- 

 tion of a laminated glandular structure; 

 this is, however, much less developed in 

 the present viviparous species than in 

 the oviparous cartilaginous Fishes, and 

 the size of the oviduct continued from 

 the glandular part more nearly corre- 

 sponds with that of the preceding por- 

 tion than in the oviparous races. Be- 

 yond the glandular portion the oviduct 

 gradually increases in diameter, having 

 its lining membrane thrown into longi- 

 tudinal plicae, until suddenly it dilates 

 into a wide uterine portion (?), in which, 

 in the viviparous Sharks, the young are 

 retained after the eggs are hatched, until 

 they are fit for exclusion in a living 

 state. 



In the dilated uterine portion the 

 lining membrane is gathered in close 

 longitudinal folds, and their free mar- 

 gins, which are beautifully wavy, contain 

 each a vessel, which follows the sinuosi- 

 ties of the fold, and sends off branches 

 to the parietes of the oviduct. To- 

 wards the terminations of the oviducts 



3 T 



