Principle in Palceontology . . 171 



Cuvier cannot be applied with confidence or successfully in 

 the classification of our fossil marsupial animals, which were 

 not discovered when Cuvier wrote. 



The authorities against Professor Owen are Professor 

 Flower, F.R.S., the eminent lecturer at the Royal College of 

 Surgeons, the late Dr. Falconer, Mr. Boyd Dawkins, and the 

 discoverer of the missing teeth, who first pointed out their real 

 position in skull and mandible, myself. 



It is a well-known fact that in highly carnivorous animals 

 the exposed portion of a tooth is completely covered by enamel. 

 This is not the case with the Thylacoleo' •& incisors, which 

 Professor Owen considers designed to *' pierce, retain, and 

 kill " ! They are almost destitute of enamel on their flat inner 

 surface, and are, comparatively speaking, less formidable than 

 the upper and lower front incisors of the striped phalanger 

 known z,s,Dactylopsila trivirgata (PI. XI. figs. 6 & 7), the nearest 

 ally (as far as incisors are concerned) to the Thylacoleo. 



The corresponding pair of front teeth in the Belidmus jlavi- 

 venter^ or " yellow-bellied flying squirrel," are more like the 

 Thylacoleo' & teeth in their structure ; but they are not so largely 

 developed as the teeth of the Dactylo2Jsila,which, comparatively 

 speaking, has the largest incisors of any marsupial animal living 

 or extinct, though only a fruit- and leaf-eating phalanger. 



The dental formula in Thylacoleo is as follows : — 



Incisors, Canines. Premolars. Molars. 



6 1—1 3—3 1—1 



2 0—0 3—3 2 



E^(- 



Professor Owen, to suit his peculiar system, arranges these 

 teeth in this manner : — 



Incisors. Canines. Premolars. Molars. 



2-2 1-1 4-4 1-1 ( 



1—1 0—0 4—4 2—21 ■ 



If the author will kindly examine the upper incisors of a com- 

 mon bettong [Bettongia rufescens, PI. XL fig. 8) and compare 

 therewith the Thylacoleo incisors which I sent him, and which 

 he figures under wrong names, he will at once perceive that the 

 " leonine marsupial " had a large pair of front incisors (which 

 correspond, as before stated, with those of Dactylopsila or Beli- 

 dceus)^ and a second and third pair behind the first, which are 

 almost identical in form with those of the bettong just men- 



* The two or three little teeth which occupied the empty sockets be- 

 hind the anterior part of the third incisor are stUl unlinown ; we do not 

 even know whether they were two or three in number. These teeth are 

 met with in all phalangers proper, but are seldom fomid perfect. 



14* 



