Uterine Fcetus of the Kangaroo. 48 1 



but principally the former), one presented not the slightest 

 indication of black on the breast, the other only a few traces 

 in the old feathers, those of the back having been much worn 

 at their edges. The godwits, unless very old birds, rarely, if 

 ever, change more than a moiety of their upper plumage in 

 spring ; and, in these birds, the retained old feathers of those 

 parts always appear much worn at their edges, and do not 

 assume the rufous colouring of such as are then put forth. 

 I have seen as many as three specimens, of the bar-tailed 

 species, all of which (judging from their size and length of 

 bill) were apparently old females, which, very late in spring, 

 when others of their kind had completed their vernal de- 

 velopement of new feathers, exhibited no symptom of change : 

 these I suspect to have been barren birds, or, perhaps, only 

 temporarily incapable of producing; but the only recent 

 example which I have seen during the present season was 

 not in a fit condition to examine. 



It is remarkable, that almost every genus of the smaller 

 grallatons presents peculiarities in its seasonal changes, which 

 will be amply described in the work to which I have before 

 referred. — July 10. 1837. 



Art. VII. Description of the Membranes of the Uterine Fa?tus of 

 the Kangaroo. By R. Owen, Esq., F.R.S., &c. Communicated 

 by the Author. 



In a paper read before the Royal Society in January, 1834, 

 I described the fcetus and membranes of a kangaroo (Macro- 

 pus major), at apparently the middle period of uterine ges- 

 tation, which in that animal lasts thirty-eight days. The 

 membranes consisted of an amnios ; a very large vitelline sac, 

 rendered highly vascular by ramifications of omphalo-mesen- 

 teric vessels ; and a thin unvascular chorion. There was no 

 placenta, nor any adhesion between the exterior membrane of 

 the fcetus and the internal surface of the mother, by the op- 

 position and interlacement of villi, or vessels, as in those 

 Mammalia in which the placenta is replaced by a uniform 

 villous and vascular chorion u the condition of the fcetus was, 

 in short, such as obtains in the viper and other ovo-viviparous 

 reptiles ; save that, at the period of developement at which the 

 fcetus in question had arrived, there was no trace of the ex- 

 istence of an allantois. In order to ascertain whether an 

 allantois was developed at a subsequent period of uterine 

 gestation, I dissected very young mammary foetuses of different 

 marsupial animals, as the Kangaroo, Phalangista, and Petau- 

 rus ; and, finding in them the remains of a urachus, and um- 



VOL. I. — No. 9. N. S. N N 



