202 Prof. J. Wood-Mason and Mr. A. Alcock. [Nov. 26, 



III. "Further Observations on the Gestation of Indian Kays: 

 ' being Natural History Notes from H.M. Indian Marine 

 Survey Steamer < Investigator,' Commander R. F. Hoskyn, 

 R.N., Commanding. Series II. No. 2." By J. WOOD- 

 MASON, Superintendent of the Indian Museum, and Pro- 

 fessor of Comparative Anatomy in the Medical College of 

 Bengal, arid A. ALCOCK, M.B., Surgeon, I.M.S., Surgeon- 

 Naturalist to the Survey. Communicated by Professor 

 M. FOSTER, Sec. R.S. Received October 9, 1891. 



CONTENTS. 

 1. Introduction. 



2. The parturient female and new-born young of Trygon walga. 

 3. The uterus and trophonemata of Trygon ivalga at the end of pregnancy. 

 4. The uterus and trophonemata of Trygon tvalga at the beginning of pregnancy. 

 5. Conclusions. 



1. Introduction. 



On the 24th of February of this year we communicated the results 

 of some observations on the uterine villiform papillre, or tropho- 

 nemata, of Pteroplatcea micrura (Bl. Schn.) and their relation to the 

 embryo, and also incidentally referred to the structure and probable 

 functions of similar uterine papillee in Trygon bleekeri and Myliobatis 

 nieuJiofii. 



We were able to show that in the pregnant females of these 

 Batoids the mucous membrane of the uterus is extended in the form 

 of elongate papillae, the entire surface of which, again, is beset with 

 tubular glands, and we were able to bring forward evidence in favour 

 of the view more especially in the case of Pteroplatwa micrura 

 that the function of these glands is to secrete a nutritive fluid which 

 i? conveyed down the pharynx and into the stomach of the embryo. 



Since the date of that communication we have been fortunate 

 enough to obtain, in the course of the " Investigator's " survey of the 

 Godavari Delta, pregnant and parturient females of Trygon u-alga, 

 Muller and Henle, a pregnant female of Myliobatis nieuliofii 

 (Bl. Schn.), numerous pregnant females of Pteroplatcea micrura 

 (Bl. Schn.), and an unimpregnated uterus of Narcine, the examina- 

 tion of which appears to corroborate the view advanced by us as to 

 the function of the uterine papillae and their relation to the embryo. 



In the case of Pleroplatcea micrura, of which species we have ex- 

 amined over a score of pregnant females, we find that the oviduct 

 is dilated into an uterus on both sides of the body equally, and that 

 each uterus may contain from one to three embryos, the usual number 

 being two. In the early stages of gestation the entire surface of the 



