1891.] Observations on the Gestation of Indian Rays. 205 



of the dorsal integument 15 mm. long and about O75 mm. in height ; 

 this is, no doubt, a vestige of the vertical system of fins, of which no 

 trace exists in the adult. (4.) The ventral fins in the young are 

 placed relatively farther back than they are in the adult, projecting 

 considerably beyond the hinder margin of the disk, while in the 

 adult they barely reach this limit. (5.) The tail is relatively a good 

 deal longer in the young. 



The young are pigmented in all respects like the adult. 



In the young one, immediately after it has left the uterus, the 

 abdomen is very tumid, its anterior wall being stretched so thin that 

 the abdominal and intestinal contents can be seen through it. On 

 opening the abdomen, its cavity is found to be almost completely 

 filled by the enormously distended colon (spiral gut), the liver, 

 stomach, and duodenum being displaced forward beneath the pectoral 

 girdle ; the rectum is very sharply marked off from the colon, and 

 appears as a narrow cord ; the oesophagus and stomach are empty, 

 but the colon is filled with bile-stained granular material, which, 

 under the action of spirit, has become a hard, yellowish-brown 

 cake, of which the weight is no less than one-sixth to one-seventh of 

 that of the entire body. 



The large relative size of the rectal gland is remarkable, not only 

 in this species, but also, we may mention, in the fcetus of Myliobatis 

 nieuliqfii and Pttroplatcea micrura. 



3. On the Uterus and Trophonemata of Trygon walga at the Close 

 of Pregnancy. 



The abdomen of the mother was laid open immediately after the 

 birth of the young ones. The right ovary and oviduct are un- 

 developed ; the left ovary is large, and the distal end of its oviduct is 

 dilated into a pyriform uterine swelling, the aperture of which 

 projects into the cloaca as a conspicuous os uteri. On opening the 

 uterus, which is much contracted when empty, we find a moderately 

 thick fibrous and muscular wall, lined internally with a mucous 

 membrane which is everywhere produced into long papillae (tropho- 

 nemata) ; these are brittle and friable. 



The trophonemata, which are cylindrical, unbranched, and taper 

 slightly from base to apex, are about 10 mm. in length and about 

 1 mm. in breadth ; and, on examination with a low magnifying 

 power, their surface is seen to be granular and much fissured. 



A transverse section through the uterine wall shows, from without 

 inwards, (1) a thin layer of fibrous tissue, (2) a layer of muscular 

 fibres cut transversely, (3) a layer of muscular fibres cut longitudin- 

 ally, and (4) the vascular submucosa and the mucosa about to be 

 described as they appear in a trophonema. 



