f'CETAL MEMBRANES OP OPOSSUM AND OTHER MARSUPIALS. 477 



that no satisfactory examination of the adjacent uterine wall 

 could be made. 



Although energetic efforts were made, no other pregnant 

 females were captured/ so that my observations upon the 

 opossum terminated at this period. I was quite convinced, 

 however, that older Marsupial embryos would show vascular 

 villi upon close examination. 



The opportunity of completing and confirming the above 

 results was due to the generous assistance of Professor Wilder, 

 of Cornell University, and Professor Chapman, of the Jefferson 

 Medical College of Philadelphia. The former most kindly 

 placed at my disposal a quantity of Marsupial material, which 

 he had procured from Australia; the latter allowed an exami- 

 nation of his valuable kangaroo foetus. To both of these gen- 

 tlemen I wish to express my hearty acknowledgments. 



Among Professor Wilder's material was a fine foetus, Avhich 

 will be referred to as Specimen 2, because, although it was 

 labelled " Removed from an Australian Marsupial," the memo- 

 randum giving the generic name was lost. The foetus was 

 evidently not that of a kangaroo, but probably belonged to one 

 of the smaller Australian Marsupials. Its external structure^ as 

 well as the character of its membranes left little doubt of this. 



Specimen 2 is drawn natural size in fig. 5, and was believed 

 to be in a somewhat advanced period of intra-uterine life. The 

 embryo had well-developed fore limbs, in which the fingers 

 were all distinct ; the hind limbs, although much smaller, 

 showed the division of the toes. The eyes were in a rudi- 

 mentary condition, but the ear-pits could be plainly seen, while 



^ All writers upou this subject refer to the difficulty of procuring females 

 during the period of gestation. The Rev. Dr. Bachman (loo. cit.) at one time 

 in the course of three days procured thirty-five opossums, not one of which was a 

 female. Audubon mentions a still greater proportion of males. At ordinary 

 periods the sexes are equally numerous. 



^ Characteristic features of advanced Marsupial embryos are the large size 

 of the tongue, the disproportion between the fore and hind limbs, the laro-e 

 mouth, and wide nostrils. In the case of Specimen 2, the subsequent examina- 

 tion of the kangaroo was further conlirmation of the fact of its being a 

 Marsupial. 



VOL. XXIII. NEW SER. I I 



