124 



MARSUPIAL " LARVAE " 



are the precise equivalents of similar bones in the Monotremata. 

 It has been held, but apparently erroneously, that these bones 

 are mere ossifications in the tendons of the external oblique 

 muscle of the abdomen, or of the pyramidalis of the same region ; 

 and vestiges have been asserted to exist in the Dog. Such 

 bonelets are undoubtedly present in the 

 Dog ; but it seems clear from their develop- 

 ment in Marsupials, as structures actually 

 continuous with the median unossified por- 

 tion of the symphysis pubis, that the 

 " marsupial bones " belong to that part of 

 the skeleton, and that they correspond with 

 the epipubis of certain amphibians and 

 reptiles. The pouch, it may be remarked, 

 exists in a rudimentary form in the males 

 of many Marsupials. 



The most salient feature in the life- 

 history of the Marsupials is the imperfect 

 condition in which the young are born. 

 The egg is no longer 

 laid, as in the Mono- 

 tremes; but curiously 



FIG. 60. Ventral surface of enough the OVU111, 



innominate bone of Kan- wMch hag the gmall 

 garoo (Macropus major), 



x . , Acetabulum ; ab, size of that of the 



supial " bone ; pb, pubic completely at the 



border ; nt, pectineal tu-r- i* / ~\ir 



bercle; *s symphysis; si, nrst division (as Mr. 



supra -iliac border ; ss, Caldwell has shown), 

 sacral surface ; thf. thy- j , , 



and this 



(From Parker and Has- 

 well's Zoology.) 



roid foramen : ti, tuber- 



osity of ischium. (From mental feature may FIG. 61. Mammary foetus 



Flower's Osteology.) , , , , of Kangaroo attached to 



perhaps be looked the te | L (Nat size>) 

 upon as a reminiscence of a former large- 

 yolked condition. The young when born 

 are small and nude : the newly born young of a large Kangaroo 

 is perhaps as large as the little finger. The young are trans- 

 ferred by the lips of the mother to the pouch, where they are 

 placed upon a teat. It is an interesting fact that they are 

 not merely imperfect foetuses, but that they are actual larvae. 

 They possess in fact at any rate one larval organ in the shape of 



