to M. Coste" s Memoir. 191 



criticisms, which I presume he considers as an adequate re- 

 turn for the pains I took in making him acquainted, dining 

 his visit to England, with the additional facts I had since ac- 

 quired, relating to marsupial oology. I stated to M. Coste 

 when he first saw the allantois in my dissected ovum, as M. 

 Gerbe rightly recollects, that I had foreseen that it would be 

 developed, and had even predicted its degree of developement 

 in my Memoir of 1834. I have stated in that Memoir, "it 

 would appear, indeed, from the examination of the small mam- 

 mary foetuses of the Kangaroo, Petaurus, and Phalangista, 

 that an allantois and umbilical arteries are developed at a 

 later period of gestation than the uterine foetus here described 

 had arrived at ; " and I added, " but it is not likely that the 

 allantois would be developed farther that to serve as a recep- 

 tacle of the urine secreted in the foetal state." And from the 

 small size and limited extent of the umbilical vein, I conclud- 

 ed that the umbilical or allantoid arteries had never been sub- 

 servient to the organization of a placenta. (Philos. Trans. 

 1834, p. 342). 



The sense of this paragraph is ingeniously nullified by a 

 mistranslation on the part of M. Coste. The words of the 

 passage in my Memoir are, " None of the above specimens, 

 (i. e. the mammary foetuses of the Kangaroo, Petaurus, &c.) 

 however, presented any trace of an umbilical vein extending 

 to the liver, and I therefore regard it as improbable that the 

 umbilical arteries spread over the chorion to organize a pla- 

 centa." In this passage the reader will see that no doubt what- 

 ever is expressed as to the ulterior developement of an allan- 

 tois, but only as to its being made subservient, as in the ordi- 

 nary Mammalia, to the organization of a placenta. Umbili- 

 cal vessels are not necessarily co-existent with a placenta : 

 they exist and are developed for other purposes in birds and 

 reptiles. — Now M. Coste, in order to deprive me, in the opin- 

 ion of the readers of his ' Reponse,' of the credit of my previ- 

 sion, translates the passage of my Memoir above quoted, as 

 follows. "Cependant aucun foetus uterin de kangaroo, de Pe- 

 taurus, n'a presente de traces de veine ombilicale, ou d'arteres, 

 qui s'etendaient au chorion pour organiser un placenta." And 

 he adds, "Or, il est generalement admis par tous les physiolo- 

 gistes, que le systeme forme par les vaisseaux ombilicaux, 

 (allantoidiens), est porte par rallantoide ; en signalent l'ab- 

 sence de ce systeme, M. R. Owen fait done, par cela meme, 

 naitre des doutes sur l'existence de cette allanto'ide." Re- 

 ponse, p. 12. 



Now, when I state that not only is this system of vessels 

 described in my text, but that it is figured in the plates, and 



