EMBRYOLOGY OF THE MARSUPIALIA. 17 



confirms Owen's observations, and adds nothing of import- 

 ance thereto. In 1884, Caldwell (8), in a paper on the 

 arrangement of the foetal membranes in Marsupials, first 

 clearly pointed out that the embryo lay in the splanchnocoele, 

 suiTounded by the invaginated upper portion of the yolk- 

 sac wall. He described the oreneral arranofement of the 

 foetal membrane in Phascolarctus cinereus, and showed 

 that the allantois in this form fuses with the discoidal area of 

 true chorion. He also referred to the membranes of M. 

 rufficollis, but in such a way as to lead the reader to 

 suppose that in this form also the allantois fuses with the 

 chorion. 



Semon (2), in 1894, described the foetal membranes of 

 Phascolarctus cinereus (confirming Caldwell's discovery 

 of the fusion of the allantois with the chorion), as w^ell as 

 ^pyprymnus rufescens. In this latter form he insisted 

 on the rudimentary character of the allantois and its non- 

 fusion with the chorion, and expressed the opinion that such 

 a condition would be found to hold good for the Macropodidae 

 in general. In 1895 I shortly stated (9) that such was 

 certainly the state for four species of the genus, viz. M. 

 parma, M. ruficollis, M. robustus, and M. major. 



The present communication deals with M. parma alone. 



External Characters of Embryo. 



The embryo, at least so far as external characters go, 

 appears to be in a somewhat earlier stage of development 

 than the previously described embryo of P. obesula. Un- 

 fortunately it is not sufficiently well preserved for sectionis- 

 ing. It has a greatest length of 10 mm., and a head length 

 of about 6 mm., and is characterised as follows : — Head bent 

 almost parallel with trunk. Prominent neck protuberance. 

 Lips not fused. Eye rounded. Lachrymal groove present. 

 Rounded external nares. Snout little prominent. Wide 

 external auditary meatus, with triangular ear-pinna. Fore- 

 limb not flexed, digits all present, and with claw Anlagen, 



VOL. 43, PART 1. NEW SERIES. B 



