OVARIAN STRUCTURES OF VIVIPAROUS BLIND FISHES. 43 



and the oviduct. Below there is no sign of a mesorectum in the 

 region of the ovarian horns, except for a short distance near the 

 base of one of them, but posterior to them there is such a mem- 

 brane, inclosing several blood vessels, and itself somewhat thicker 

 than the mesovarium above. It is also clear from an examina- 

 tion of this ovary that, as will be noted more particularly below, 

 the egg-bearing tissue, the ovary proper, forms a thick median 

 partition in the ovisac. 



The external appearance of the ovary agrees very closely with 

 Eigenmann's description (op. cit., p. 418) of that of Cy matog aster : 



" The ovary is' a spindle-shaped bag, divided anteriorly into 

 two arms which indicate the bilateral origin of the present struc- 

 ture. One of these arms, the left, is usually smaller than the 

 other. . . . The ovaries of the two sides have evidently been 

 united from behind forward, so that externally only the two an- 

 terior horns show the bilateral structure, and one of these horns 

 seems to be in process of phylogenetic resorption." 



While there is frequently a difference in the size of the two 

 horns in Lu'cifnga and Stygicola, there is no uniformity in this 

 matter. There seems to be no evidence that the right or left 

 portion of the ovary is "in process of phylogenetic resorption." 

 Ryder found that in Gainlnisia patrnelis " the ovary is a simple 

 unpaired organ, the greater part of which lies on the right side 

 of the body-cavity below the air bladder. . . ." 



The size of the ovary varies, of course, with the age and size 

 of the female, as well as with the state of development of the ova 

 or embryos contained in it. One female of the genus Litcifiiga, 

 which had a length of 65 mm. and which contained four foetuses 

 nearly ready to be born, had an ovary with a length --measur- 

 ing to the extremity of the longer horn --of 16 mm., and a di- 

 ameter of 8 by 9 mm. As the foetuses were 1 8 to 20 mm. long, 

 it was not surprising to find that their tails were bent over. An- 

 other female of the same genus, 83 mm. long, had evidently 

 given birth to young only a short time before her capture and 

 had an ovary 12 mm. in length. 



The point of division into the two horns is usually about five 

 twelfths the distance from the anterior tip of the ovary to its pos- 

 terior end. As already stated, the two horns rarely show equal 



