BY J. T. WILSON. 683 



<h'nithorhyticlius would seem to differ from that of the kindred 

 genus Echidna, in whose case there is ample evidence that the 

 mammary foetus is borne about, either occasionally or habitually 

 by the mother.* (The incubating egg itself seems to be carried 

 in a temporary pouch in Echidna.^). Here the very imperfect 

 marsupium or bilateral pouch-like fold of the integument, wiiich is 

 present during lactation, affords at least a partial support in 

 default of a nipple, while a similar pouch appears to be lacking 

 in the Oruitkorhynchus. 



In vieAv, therefore, of the rarity of examples of what I have 

 already referred to as the "mammary foetus" of the platypus, the 

 present description of one that I believe to be slightly younger 

 than any hitherto described may be not unwelcome to comparative 

 anatomists. 



For this very valuable acquisition I am greatly indebted to the 

 liberality of the Ti'ustees of the Australian Museum in Sydney, 

 who were good enough to place it at my disposal along with a 

 young Echidna to enable me to continue certain investigations 

 into the anatomy, more particularly of the head, of the Mono- 

 tremes. 



It is to be hoped that ere long we shall have mcjre abundant 

 light thrown upon the embryology and foetal anatomy of Orni- 

 thorhyuchus and Echidna from the researches of European 

 anatomists into the developmental material w^hich we are led to 

 believe has been accumulated at consideraljle ex]iense by both 

 English and German naturalists. 



It is perhaps permissible in the interests of British science to 

 express a keen regret that hitherto so little has come to light as 

 pi-oduct of Mr. Caldwell's fully equipped expedition of over ten 

 years ago. It is indeed somewhat humiliating to English-speaking 

 zoologists that after the highly auspicious beginning and the 

 apparently successful conclusion of that important and long- 



*Owen: "On the marsupial pouches, mammary glands, fee, of the 

 Echidna hy.^trix." Phil. Trans. 1865, pp. 671-86. 



tHaacke, W. : " On the marsupial ovum, the mammary pouch and the 

 male milk glands of Echidna hystrix." Proc. Rov. Soc. .\xxviii. p. 72. 



