338 Mr Owen on the Dicynodon. 



otherwise edentulous jaws of a bird or turtle. Yet if we con- 

 sider the fact in its relations to the exigencies and convenience 

 of the living animal, the wisdom and beneficence of the prin- 

 ciple is apparent, and the departure from the ordinary rule 

 manifests a power transcending the trammels of scientific sys- 

 tem. The teeth of the Dicynodon being but two in number, 

 and their use to the animal indicated by their unusual size to 

 be of unusual importance, the inconvenience and detriment 

 that must have ensued from frequent shedding and replace- 

 ment is very obvious ; -we may readily conceive it to have been 

 incompatible with their functions, and therefore abrogated in 

 favour of another mode of renovation which is abnormal in 

 reptiles, simply, perhaps, because the form, proportions, and 

 function of such tusks were unique, and are now no longer 

 manifested in a cold-blooded class. 



Some observations may be naturally expected in reference 

 to the probable use of the tusks to the Dicynodons, and the 

 mode of life of those ancient and most remarkable saurians. 

 In the Mammalian class, where alone we now find the analo- 

 gous instruments, tusks are usually given as weapons of offence 

 and defence, — an office exemplified in the hornless musk-deer, 

 the boar, and in the large canine teeth of the Carnivora. The 

 elephants use their tusks chiefly, though not exclusively, as 

 lethal weapons : the Walrus is said to apply his tusks to aid 

 in clambering over icebergs, as well as in combat and defence : 

 the Dugong is supposed to wear the exserted points of the 

 tusks in detaching fuci for food. Such an office at first sug- 

 gests itself as a very probable one in regard to tusks descend- 

 ing, like those of the Dugong, from the upper jaw, and com- 

 bined with edentulous and probably horny mandibles like 

 those of a fucivorous turtle. 



On inspecting the remains and the impressions of the tusks 

 in the fossils under consideration, and especially in the almost 

 entire skull of one species, the Dicynodon lacerticeps, we per- 

 ceive that these weapons are sharp-pointed, and present no 

 trace of that obliquely bevelled or chisel-shaped extremity 

 which is produced by habitual application in acts of obtaining 

 daily food, as, for example, in the protruded extremities of the 

 tusks of the Dugong and the incisors of the Rodents. The 



