ORNITHORHYNCHUS 



ORXITHORHYXCHl-.S. 



lit 



He therefore group** them both under the 

 ad at UM ame time i proved hit opinion that 

 the generative proeeei difiered considerably from that of the true 

 lM, reetlnc that opioioo on the peculiarities of the organs 

 I for reproduction, and on the absence of nipple* in both sexes, 

 r in the female 0m.rAr*yriU. 



f St-Hilaire wat not tardy in adopting the opinion of Sir 

 He constituted a new order for theee linage forms, and a 

 ha*ty dissection hairing led him to conclude that the genital product* 

 of both Mice, at weU u the urine and faxea, had their Uue by a 

 I outlet, he gate to that order the name of Monotremes. Hit 

 rare that both mammary gUn.li and nipple* were wanting, 

 account! of the diaeoTery of eggs of the Onitkorhynthiu 

 if hie belief la the oriparooi character of the Monotremes, 

 he separated that order from the ilammali*. 



Many diflVreot opinion* were entertained by subsequent anatomist* 

 and Boolofista, and it wai not till the paper* of Professor Owen wen 

 published that many doubtful poinU in the structure and habiU of 

 thi* animal wen settled. The first of these papers, ' On the Mammary 

 Olande of the Oratthorbynchu* Paradoxus,' was read before the Royal 

 Society (llet Jane, 1822), and published in 'Phil Trans.' for 1832, 

 part ii. ; the second, ' On the Ova of the Ornithorhynchu* Paradoxus/ 

 was read before the same society on the 19th June, 1834, and is pub- 

 lished in 'Phil Trans.' for 1834, part ii. ; and the third, 'On the 

 Young of the Omithorhynchns Paradoxus,' was communicated to the 

 Zoological Society of London on the 27th May, 1834, and is published 

 in the first relume of the ' Transactions ' of that society. 



From theee papers we derive the following details of the structure 

 and economy of this enature. 

 The dental formula of OnutkorkyneJnu may thus be noted 



molars, - ' 8 ; although the organs thus noted are really not 

 tn* teeth. 







Teeth of OrnUa*r*yiw*ic. P. Curler. 



The cranium, though widely differing from that of other mammal*, 

 bee more cJacety to the cranial type of that class, a* 

 , than to any other. It is rounded, wider than it is high, and 

 cither sagittal or occipital orest. It is narrowed and flattened 

 between the orbiu, which are small and directed upward-. The 

 MMd* afUiwaide become* flattened and widened again, and preeenU 

 on each aid* a email hook or prooeas above the tuborbital hole ; it 

 * bifurcate, and iu two flattened and slightly-divaricating 

 bate each by an involute kind of hook. The zygomata 



rMMhi 



ru*a. * uv "jy rlllMWJ 



rebee an nctUfateal and high vertically, and at their upper border i* 

 n msrtirl pott-orbttary apuphyaia. Under their anterior baas the 

 axillary bone form* a nearly horizontal Battened surface, to which 

 Ike two molar, adhere. Their posterior base above the gleooid facet 

 is aimed with a hole which commnntoatee from the temple to the 

 ootW. The *otire palate ia plain, and is continued (narrowing rod- 

 deJrbeU^ the aMkn) to the oral bole.; nptothispoint theieptum 

 of tail Dortril* remain* boar/. The tympanic cavitie* are very small, 



M I* WW QeWMF UM 



Cavier 



maetoid apophyaia In the form of a 

 only detect in his specimen* two clear 

 _ the anterior hooka, and that which eepa- 



Mary from the palatine bone*. The poaition, the implan- 



of the teeth, and the paaaage of the enborbital canal, well dUn* 

 the maxillary booe. The nook-lilt. bonea, which are as it were set fa 

 tha. m*\>,\f. appew to be th. tetotrnxillary bonea. Between 



**""J*" b '"T^'JL^" 1 "*"* * "^f- t VP 

 HflMn, a small bone, which ha* an upper plane divided into two 



by a furrow, a lower plane notched on each side, and a vertical plane 

 uniting the two other*. In the neighbourhood of this bone the 

 nostrils are pierced, and it may be taken to represent the nasal bones 

 and the palatine portion of the intermaxillary bones. In the anterior 

 angle of the orbit is a very small lachrymal and a large suborbital hole. 

 This last gives origin to a canal which opens in front of the small hook 

 on the side of the muzzle ; it is divided into two by the lateral carti- 

 lage of the beak. There comes besides from this canal a hole which 

 opens in the palate under the preceding, and another which, after 

 having formed a long canal, opens at the aide of the intermaxillary 

 bone, and consequently in the edge of the osseous beak. Between the 

 first of theee three suborbital holes, a little higher, is a small hole which 

 communicates with the aperture of the orbit, pierced in front of the 

 optic, and which Cuvier believes to be analogous to the anterior orbital 

 hole. The first he thinks answers the supra-orbital hole in man. The 

 ingle hole, analogous to the apheno- and pterygo-palatinc, is pierced 

 in the lower part of the orbit, a little behind the suborbital canal. It 

 enters also in the nasal canal and in the palate near the first molar. 

 Tho optic hole is very large, and the spheno-orbital equals it ; the 

 oval hole is very large and distinct Between the two oval holes ore 

 two membranous spaces. There are behind two very large holes at 

 the place of the condylodians, but Cuvier supposes that they comprise 

 also the jugulars. Internally the inequalities are but little marked. 

 The sells, which is but little elevated, is hollowed out in the middle 

 by a longitudinal canal, and terminated backwards by a clinoid and 

 very elevated lamina. The most curious internal part is the ethmoidal 

 fosset, which is small, and has only a single hole of no great size for 

 the olfactory nerve, and perhaps another very small one ; on each side 

 are spaces, purely membranous, to separate it from the canal of the 

 suborbital nerve. The three semicircular canals project far inwards, 

 and intercept a very remarkable hollow. Here may be traced many 

 characters in which the skull of the Ornithorhynchut approaches those 

 of birds. The bony tentorium is scarcely perceptible, but there is 

 and this U very remarkable a large longitudinal osseous falx. 



Skull of Omithm-hynehia. 

 a, wen from above ; t, tern from below ; c, ten from behind. 



Lower jaw of OniHork^nckia, w*n from abor*. 



