PURBECK FORMATIONS. 



99 



[Erinaceus) adds young Rabbits to its miscellaneous and lower animal diet, and kills them 

 as eflTectually by its approximate laniaries as does the Stoat by its divaricate ones. 

 Breeders of poultry will hardly be prepared to endorse the epithet " mild " applied by 

 Prof. Flower to " the ferocity and destructive power " of the Rat as compared with the 

 Ferret ;^ if the application of their respective lethal weapons upon defenceless birds be the 

 suljject for consideration. No doubt, in combat, the Terrier or the Ferret gets the better of 

 the carnivorous rodent. We may admit that Triconodoii mordax, the contemporary of the 

 Plagiaulax minor, might have overcome and devoured that little predatory Diprotodont ; 

 but this would afford no gi-ound for denying the power of the latter to pierce and slay, by 

 means of its approximate laniaries, the comparatively defenceless Saurilli, Macellodi, 

 Nuthetes"' and other diminutive lacertines. 



In the Insectimra, as in the Marsupialia, there are two local conditions of the teeth 

 which are adapted " to pierce, retain, and kill." In some, e.g. Gymnura, Dasyurus, the 

 laniaries answer, in position, to the canines of gyrencephalous Carnivora, and ' are held 

 well apart through the interposition of a line of incisors : ' in others, e.g. Pofamogule (fig. 

 16), Solenodon, Erinaceus, Scalops, Urotrichus (fig. 17), Plagiaulax, Thylacoleo (fig. 18), 

 the laniaries are approximate, or are separated at their base by only a single pair of 

 minute incisors (fig. 16). 



Fig. 17. 



Fig. 18. 



Front view of upper and lower laniaries, 

 Urotrichns ia/po'ides, magn. 



Front view of lower incisive laniaries, 

 size, Thylacoleo earnifex. 



The transference of the laniary form and function from the canines to the incisors, the 

 development of the latter locally characterised teeth into lethal weapons, is the rule in the 

 lissencephalous members of Cuvier's ' Carnassiers.' Whether, however, the laniaries, which 

 " are kept well apart " in Moschus, as in Felis, or which are approximate in Plagiaulax 

 as in the many predaceous species above cited, be really used to pierce, hold, and kill other 

 animals for food, cannot be detemiined in an extinct species " by a facile observation of 

 mere form," ' but by the laws of physiological correlation. Referring to the molars of 



' 'Quarterly Journal of the Geological Society,' vol. x.^iv (1868), p. 318. 

 2 Owen, ' Quarterly Journal of the Geological Society,' vol. x (1854), p. 420. 

 s Falconer, 'Quarterly Journal,' &c., p. 35S, ' Palasontological Memoirs,' p. 441. 



