42G On Vtero-gestation in Trygon Bleekeri. 



[The colours of the mother are dark brown dorsally and olive- 

 brown ventrallj, except on the thorax and abdomen, wliich 

 are blotched with white.] 



§ 7. Heca'pitalalion and Conclusion. 



To recapitulate : in Trygon Bheheri, as twice observed in 

 the pregnant state, we find a single uterus containing a single 

 naked foetus unattached structurally to the mother; we find 

 tiie uterine mucous membrane to be produced into long villi 

 wliich consist almost exclusively of blood-vessels and glands ; 

 and we find the viscid, turbid or milky, and richly albuminous 

 secretion of the latter free in the uterine cavity. In the 

 present case the secretion is observed unchanged in the 

 spiracles, and in coagula filling the " duodenum " and the 

 anterior part of the spiral gut, of the foetus. 



Elsewhere Professor Wood-Mason and I have shown that 

 in the nearly related Fteroplatcea micrura the uterine villi 

 (trophonemata) actually pass into the spiracles of the foetus; 

 and I have quite recently observed this same disposition of 

 the trophonemata in Trygon walga. 



The specimen from which these particulars have been 

 recorded was too large for preservation ; its skin has been 

 sent to the Indian i\Iuseum. 



Besides the classical text-books and the classical memoir of 

 Johannes Miiller, " Ueber den glatten Hai des Aristoteles " 

 (Abhand. Ak. Wiss. Berl. 1840), the following papers refer 

 specially to the subjects of the uterine villi and aplacental 

 viviparity of the Batoidei : — John Davy, " Observations on 

 the Torpedo," Phil. Trans. 1834 ; Trois, " On the Uterine 

 Villi of Myliohatis noctula [and Centrina Salviani'\,^^ Atti 

 del Instituto Veneto, vol. ii. ; Haswell, P. L. S., N. S. Wales, 

 vol. iii. 1889, on Urolojyhus; Alcock, " Observations on the 

 Gestation of some Sharks and Rays," Administration Report 

 of the Marine Survey of India for the Official Year 1888-89, 

 and Journ. As. Soc. Beng. vol. lix. part ii. ( Trygon Bleekeri 

 and Myliohatis Xieuhojii) ; Wood-Mason and Alcock, '' On 

 the Uterine Villiform Papillro oi Pteroplativa micrura^^'' Proc. 

 Roy. Soc. vol. xlix., and " Further Observations on the 

 Gestation of Indian Rays," Proc. Roy. Soc. vol. 1. {Trygon 

 ivalga, Pteroj)laicea micrura, and Myliohatis Xieu/iojii). 



EXPLANATION OF PLATE XIX. 



Ft;/. \. The distal lialf i>f a tiopbonenia, X 10, showing m, the nou- 

 glandular uiaigiu iu which nms a, the arterv ; ni d <;, the glan- 

 dular centre with r, the central vein. 



