258 THE INCISORS OP SCEPARNODON, 



THE INCISOKS OF SCEPARNODON. 

 By C. W. De Vis, M.A., Corr. Mem. 



(Plate xxii.) 



The haze of ignorance still shrouding the origin of the teeth we 

 call Sceparnodon would be lightly lifted if only we could opine 

 with the author of Pt. 5 of the British Museum Catalogue of 

 Fossil Mammals, that they grew in the upper jaw of Phascolonus. 

 But even in the realm of the undemonstrable it would be well that 

 an explanation to be projected thence should not wholly ignore 

 the fact, intimated by Owen, that these teeth are not all the same 

 teeth ; well, also, that it should not, in the act of associating them 

 with any mammal whatever, raise a crop of difficulties for other 

 explanations to eradicate. To a waiter on reliable means of judg- 

 ment it has now become evident that any attempt to refer these 

 teeth to an animal whose lower incisor is known must end in 

 disaster. In other words, it is patent that the teeth in our collec- 

 tions are not all, as they are assumed to be, upper incisors, but 

 that they include the teeth from both jaws of the otherwise 

 unknown animal. Though the assertion is a bold one, it is made 

 with the diffidence which arises, not from any weakness in the 

 evidence, but from the reflection that the means of distinguishing 

 one tooth from the other has always been in view of keen and 

 practised eyes yet has never been recognised. Turning to Plate 1 1 

 of the Philosophical Transactions of London for 1884, and com- 

 paring fig. 5 with fig. 7, we observe that the length of the working 

 surface in fig. 7, though diminished by the absence of somewhat 



