16 JAS. p. HILL. 



III. On the Foetal Membranes of Macropus parma. 



The following account of the foetal membranes of this 

 small wallaby is based on the examination of a single em- 

 bryo from the left uterus, for which I am much indebted to 

 my friend Mr. J. J. Fletcher, M.A., B.Sc. 



Historical. 



In 1834, Owen (4) gave an account of the foetal membranes 

 of an embryo of M. major, 7 lines in greatest length; but 

 although no allantois was found in this embryo, he stated, 

 from the presence in young mammary foetuses of " the Kan- 

 garoo, Phalangista, and Petaurus," of ''the remains of 

 a urachus and umbilical vessels," that '' it would appear that 

 an allantois and umbilical vessels are developed at a later 

 period of gestation, but probably not to a greater extent 

 than to serve as a receptacle of urine" (4, p. 342). The 

 accuracy of this conclusion he definitely established in 1837, 

 through the examination of a uterine embryo of M. major, 

 10 lines in length. He says (5, p. 83), " Below the neck of 

 this [vitelline] sac there is extended a second pyriform sac, 

 about one sixth the size of the vitelline sac, having numerous 

 ramifications of the umbilical vessels and constituting a 

 true allantois. This sac was suspended freely from the end 

 of the umbilical cord ; it had no connection at any part of 

 its circumference with the chorion, and consequently was 

 equally free from attachment to the parietes of the uterus in 

 which the foetus was developed."' 



Between 1837 and 1881 nothing of importance seems to 

 have been published on the embryogeny of Macropus. In 

 the latter year Chapman again described (7) the foetal mem- 

 branes of M. major, " six eighths of an inch in length from 

 the mouth to the root of the tail." His account essentially 



* Owen states that he was anticipated in the description of the allantois of 

 this embryo by Coste (6), with whom he had examined the foetal membranes. 



