410. Though this argument appears to be of considerable weight, yet CAMPER, who was greatly skilled in comparative anatomy, and who had studied this subject with particular attention, was of opinion, that these grinders belong to a species of elephant. This opinion he states in a letter to Pallas, who had found grinders and other bones of this same animal, on the western declivity of the Ural mountains.[219] Camper denies that the animal is carnivorous, because the _incisores_, or canine teeth, are wanting; and he argues farther, from the weight of the head, which may be inferred from the weight of the grinders, that the neck must have been short, and the animal must have been furnished with a _proboscis_. He afterwards abandoned the latter hypothesis, and gave it as his opinion that the _incognitum_ was neither carnivorous, nor a species of the elephant.[220] [Footnote 219: Acta Acad. Petrop. tom. i. (1777,) pars posterior, p. 213, &c.] [Footnote 220: _Ibid._ tom. ii. (1784,) p. 262.] 411. Nevertheless, CUVIER, in a _mémoire_ read before the National Institute of Paris, maintains, that the fossil bones of the new Continent, as well as most of those of the old, belong to certain species of the elephant; of which, at least, two do not now exist, and are only known from remains preserved in the ground. He distinguishes them thus:[221] [Footnote 221: Mémoires de l'Institut National, Sciences Physiques, tom. ii. p. 19, &c.] _Elephas mammonteus_,--_maxillâ obtusiore, lamellis molarium tenuibus, rectis_. _Elephas Americanus_,--_molarities multicuspidibus, lamellis post detritionem quadric-lobatis_. The latter species, which is meant to include the _animal incognitum_, is said to have lived, not only in America, but in many parts of the old Continent. Yet some late inquiries into the structure of the teeth of graminivorous animals, and particularly of the elephant, make it very improbable that the _incognitum_ has belonged to this genus.[222] The grinders of the elephant have been found to consist of three substances, enamel, bone, and what is called the _crusta petrosa_, applied in layers, or folds contiguous to one another; and no vestige of this structure appears in the grinders of the unknown animal of the Ohio.[223] At the same time, Dr Hunter's assertion, that this animal was carnivorous, is rendered doubtful, not only by the want of _canine_ teeth, but also from the resemblance between its grinders and those of the wild boar, which Mr Home has observed to be considerable.[224] The grinder of the boar is similar to that of the elephant, in the extent of the masticating surface, but not at all in the internal structure; and the same is true of the tooth of the _animal incognitum_, so that a considerable probability is established, that it and the boar are of the same genus, and both destined to live occasionally either on animal or vegetable food.