Prof. Owen on the Generative Economy 0/ Echidna hystrlx. 421 



with its fibrous or muscular layer, is thin, not exceeding -^th of a 

 line in the present specimen. The inner layer of the uterine wall 

 is the thickest, and chiefly composes it, consisting of fine lamellae 

 stretched transversely between the fibrous layer and the fine smooth 

 lining membrane, the whole being of a pulpy consistence, and doubt- 

 less in the recent animal highly vascular, especially in the impreg- 

 nated state. The lining membrane was devoid of any trace of vas- 

 cular connexion with the membranes of an ovum or foetus, and was 

 thrown into delicate irregular rugae, which assumed the longitudinal 

 direction at the " cervix" or contracted terminal part of the uterus. 

 The orifice on the "os tincae" was a puckered slit, about a line in 

 extent ; below it, on a produced or papillose part of the prominence, 

 was the small circular orifice of the ureter. 



The right ovarium was proportionally more developed and larger 

 than in the Ornithorhynchus paradoxus : three ovisacs were de- 

 veloped and attached, as in the left ovarium ; and there was also a 

 compressed ovisac, similar in size and shape to that in the left side, 

 and exhibiting an apical cicatrix, whence it is to be inferred that, 

 in this instance, the right as well as the left ovarium had furnished 

 an impregnated ovum ; and the near equality of size and close simi- 

 larity of structure and condition of the right oviduct and uterus 

 equally indicated that they had participated in the functions of the 

 last season of generation. 



The urinary bladder opened into the middle of the fundus of the 

 urogenital compartment, the uterine orifices intervening between the 

 vesical one and the ureters, as in the Ornithorhynchus paradoxus. 

 The uro2;enital canal is 1 inch 4 lines in length, and about 9 lines in 

 diameter ; its inner surface shows by some coarse wavy longitudinal 

 rugae its capacity for dilatation. The rectum was here of great 

 width ; it terminated by a contracted puckered aperture in the back 

 part of the beginning of the vestibule, behind the aperture of com- 

 munication of the urogenital with the vestibular canal. The distal 

 half of the vestibule is lined by a denser and less vascular epithelium 

 than the proximal one. The author concludes, from these appear- 

 ances, that the present Echidna had produced two young, of which 

 only one was secured, and that probably she had a mammary foetus 

 in each pouch prior to her capture. 



The one which was secured resembled the young of the Ornitho- 

 rhynchus in the general shape and curvature of the body, and also 

 resembled the new-born young of the Kangaroo in the proportions 

 of the limbs to the body, in the inferior size of the hind pair, in the 

 degree of development of the digits, especially of the fore pair, and 

 in the feeble indication of eyes or eyelids. But the mouth is pro- 

 portionally wider, and has the form of a transverse slit ; it is not 

 circular. Upon the upper lip, in the mid line between the two 

 nostrils, is a small protuberance corresponding to that in the young 

 of the Ornithorhynchus paradoxus^ which had been covered by some 

 epidermal production. The traces of ears are less conspicuous than 

 in the young Kangaroo, the conch being little, if at all, developed 

 in the mature Echidna. 



