1893.] un. M. F, AvooDWAED OX :^[A■^rMALIA^^ de;ntition. 463 



lower incisor is present as in Pefror/ale with a rudimentary suc- 

 cessor, the functional incisor being {„ and shows a distinct indica- 

 tion of its successor in the second dentition (fig. 11, r') ; no trace 

 of iy was observed. 



The canine is large and late to calcify, being uncalcified in the 

 largest specimen examined, of which the head measured 83 mm. 



In the diastema between the canine and the 3rd premolar, the 

 dental lamina presents numerous small enlargements and irregu- 

 larities, some of which possibly represent the missing premolars. 

 In the lower jaw, howeAer, there is a very distinct vestige of a 

 tooth in the form of an irregular enamel-organ with enamel- 

 epithelium and pulp (fig. 1-4). This, from its proximity to the 3rd 

 premolar, must represent jjn).^. 



The one functional successional premolar in the youngest speci- 

 men examined is developed as an enlargement of the dentid lamina 

 between pm^ and pm^ (fig. 21), being continuous A\ith the slight 

 downgrowth developed on the inner sides of those teeth (figs. 20 

 and 22), In this respect it differs slightly in origin from that of 

 Pdrogale, where it was chrectly continuous with the enamel-organs 

 themselves, and not with any internal lamina ; this may be due to the 

 specimen under consideration being older than the Petrof/cde, as even 

 in that form this tooth subsequently takes on this internal position. 



These two slight downgrowths (figs. 20 and 22) may perhaps 

 represent rudimentary permanent teeth, in which case the two 

 functional pi'emolars must both be regarded as belonging to the 

 first dentition. 



In the older specimens the successional premolar subsequently 

 takes on a position internal to the posterior end of jjh?^, and loses 

 its connection with jmi*, u ith which its connection was at the best 

 very sliglit. 



In the youngest specimen the 1st molar above and below was 

 just formed, and \Ahile the lower one showed no indication of any 

 accessory tooth rudiment, the upper one (fig. 26) had exactly the 

 same relationas seen in Pdrof/ale ; that is, a downgrowth of epitlio- 

 loid cells from the dental lamina external to and nearer the gum 

 than the molar itself. Tliis, as I have before pointed out, must be 

 regarded as a vestige of the 1st dentition, and the molar teeth, at 

 any rate the 1st, must be regarded as belonging to the 2nd dentition. 



MaCROPUS BEXNETTIl (RUFICOLLIS). 



One very badly preserved head. This, when clarified, showed 

 that there were present in the ])remaxilla 5 incisors, the three func- 

 tional being i\ i\ and i", and the two vestigial ones being i^ and i''. 



The dried skull of a very advanced pouch foetus showed that 

 the canine was very large for a Macropus and calcified, anrl I 

 should think in all probalnlity cuts the gum and is shed, not 

 reabsorbed. The first specimen was loo much macerated to nuike 

 out any detailed tooth relationships, and I oidy mention it here to 

 show how constant is the presence of at least two of these 

 vestigial incisors (viz. i'' and i'). 



