136 



THE EXTERNAL CHARACTERS OF POUCH EMBRYOS OF 



MARSUPIALS. 



No. 6.— DASYCERCUS CRISTICAUDA. 



By Frederic Wood Jones, D.Sc, F.Z.S., 

 Professor of Anatomy in the University of Adelaide. 



[Read July 12, 1923.] 



Of this somewhat rare and particularly interesting pouched-mouse I have 

 been able to examine the external characters of fourteen young specimens. 

 These embryos constitute two litters — the one a series of seven, which measure 



Fig. 1. 



Dasyccrcus cristicauda. 



Hair tracts of a male embryo, 25 mm. R.V. length. 



15 mm. in R.V. measurement; and the other, also a brood of seven, which are 

 10 mm. longer in the same measurement. For all these yoimg animals I am 

 indebted to Mr. A. G. Bolam, of Ooldea. who forwarded the female animals, 

 the one dead and preserved in spirit, and the other living. 



The living animal was received on August 15, 1922. and she and her young 

 were under close observation until September 17, on which day she unfortunately 

 died. The very rudimentary condition of the marsupium, by which all the 

 developing young are freely exposed for inspection upon the ventral surface of 

 the mother, makes their study a particularly interesting one. The young animals 

 were 25 mm. in R.V. length when the mother died. They freed themselves from 

 the nipples after her death and were very vigorous, but they were impossible to 

 rear by artificial methods. 



