38 ARTHUR ROBINSON. 



growth of the broad ligament, the increase specially affecting that 

 portion of the ligament which lies ventral to the attachment of the 

 ovary. As a result a deep sac is formed, which extends forward 

 beyond the ovary and hangs down below it. The orifice of the sac 

 tends to be turned toward the mesial plane of the body, and the 

 ovary occupies the upper edge of the orifice of the sac, while the 

 Fallopian tube opens on the lower edge. An example of a pouch 

 thus formed is found in Ccelogenys paca ; but a still better marked 

 example is presented by Cynocephalus porcarius. 



The direction of the orifice of the sac depends upon the lengthening 

 of the Fallopian tube, and upon the increase in extent of the broad 

 ligament lying ventral to it. If the increase of the peritoneal fold 

 is comparatively great the sac hangs down below the ovary, and the 

 orifice of the sac looks upward and inward towards the vertebral 

 column, as described by M. Watson in the Indian Elephant.* If at 

 the same time the Fallopian tube is much elongated, it forms folds 

 and convolutions in the outer wall of the sac. 



The next step in the completion of this ovarian sac is brought 

 about by the adhesion of the edges of the adjacent folds, as follows : 

 The free edge of the broad ligament, between the uterus and the 

 posterior extremity of the orifice of the oviduct, becomes adherent to 

 the edge of the fold caused by the ovarian ligament. 



In this manner the pouch is rendered more sacciform, and its 

 opening into the peritoneal cavity is reduced to a mere slit, equal 

 to or slightly exceeding in length the long diameter of the ovary. 

 On the upper edge of the slit the ovary is placed ; on the lower 

 edge the orifice of the oviduct is found. A good example of a 

 pouch thus formed may be found in the guinea pig, in which animal 

 the Fallopian tube is folded and convoluted in the outer wall of the 

 sac, and another in the porcupine. Ovarian peritoneal pouches, 

 similar to those above mentioned, have been often figured and 

 described. They have been found in the seal,f in Eycma crocuta,% 

 in the wombat,§ in the rabbit, the guinea pig, bitch, in insectivores,|| 



* Trans. Zool. Soc, vol. xi., part iv., p. 114. 



t Turner, Trans. Roy. Soc. Edin., vol. xxvii., p. 277. 



I M. Watson, Trans. Zool. Soc, vol. xi., p. 114. 



§ Owen, Anat. Vert., vol. iii., p. 680. 



|| Owen, loc, cit,, vol. iii., p. 688. 



