1891.] Uterine Villiform Papilla of Pteroplatsea micrui'a. 367 



affluent sinuses. Hence in lightly- stained trophonemata, examined 

 entire under a lower power, the artery is only just visible by trans- 

 parence, while the vein presents itself as a very distinct, branched, 

 and tapering dark streak. 



The connecting system of sinuses occupies the plane between the 

 layer of glands of opposite sides, sending off processes around the 

 base or specially secreting portion of every gland. 



The glandular epithelium possesses no connective tissue framework 

 eyoud a filmy nucleated gauze, shreds of which can be traced wher- 

 ever vacuities occur between the bases of adjoining glands, the 

 rhole trophonema consisting, as has already been stated, almost 



3ly of epithelium and blood vessels. 



Having already stated our conclusion as to the function of the 

 jphonemata in Trygon and Pteroplatcea, and having described the 

 path taken by the secretion in the latter, it only remains to consider 

 riefly how far other views of the manner of absorption by the 

 ibryo of the nutrient uterine milk might apply in the case of these 

 two fishes. Whatever may be the case in the earlier stages, in the 

 later stages, at any rate, branchial filaments do not absorb nutriment 

 3m the maternal wall, for branchial filaments do not then exist. 

 Again, absorption through the general surface of the body of the 

 ibryo can hardly be looked upon as the principal channel of supply, 

 luse the embnyo, at least in its later stages, is so folded or rolled 

 as to leave as little extent of surface as possible available for 

 Drption. 



[P.S., April 8, 1891. Since the above was written and despatched, 

 have had the good fortune to obtain from amongst the contents of 

 fishermen's nets at Cocanada several pregnant females of 

 roplatcea micrura. The examination of these specimens in the 

 esh state, while it confirms our description in its principal particu- 

 lars, renders some modification of it necessary. (1.) The number of 

 ig may be as many as three in each uterus, both uteri being 

 reloped. (2.) The number of young may be two in each uterus, 

 ir first qualification will therefore be, Uterus well developed on both 

 les ; each uterus may contain from one to three young ones. Again, 

 lere two and three young ones exist, the trophonemata (which 

 pear to be fairly well developed over the entire mucosa of the 

 srus) are specially long opposite to the spiracles of the young one, 

 which they pass. Apparently and this will be our second quali- 

 itton in the early stages of gestation the trophonemata are equally 

 developed over the entire surface of the uterine mucosa, but by the 

 ire exerted by the groiving embryo they become greatly atrophied, 

 on those spots where they can pass into the spiracles of the embryo, 

 here, perhaps by compensation, they become hypertrophiedJ] 



