to the annexed wood-cut, in which the darkened spots indicated by the line running from _a_ denotes the permanent tooth already through the gum and in the mouth, though still covered and partially concealed by the retained table of the temporary grinder _c_. The appearance of the table of the temporary molar when cast off is shown in the figure immediately underneath, to which the letter _c_ is also affixed, and the projecting portions ascending from its edges exhibit the last remnants of what originally was the fang: _b b_ are molars, well up and worn to a level. [Illustration] The next wood-cut exhibits the molar _a_, immediately after it has lost its covering. At this time the table is very uneven, presenting points which the finger would readily recognize, but in a short time these wear off, and an even surface is obtained, rendering it level with the other teeth, _b b_. [Illustration] As is here seen, when the crown has been removed, the permanent molar is well up, although it occupies the same place, and fills the same alveolar cavity which the temporary molar originally held. The horse incisors do not occupy the same cavities in which the milk incisors were placed, but are developed in cells formed especially for their reception, and come up rather behind than absolutely under the primary teeth. The form of the anterior part of the jaw in the foal admits of such an arrangement, and its greater comparative bulk gives all the space that was required. The space, however, between the branches of the lower jaw where the molars are developed, is filled by important muscles; and while any thickening externally would deteriorate from the symmetry of the head, any internal enlargement would have interfered with the free motion of the tongue and hyoideal appendages, the movements of both being as essential to perfect mastication as the presence of the teeth themselves. Hence the grinders are in their development regulated by a different law to the incisors; nor is the ordinization which declared the first should be well up, and the last scarcely to be seen when the period for casting off the temporary teeth arrived, to be passed over in silence. The molars are more important to the welfare of the animal than the incisors can be supposed to be. If the front teeth are irregular, the horse, nevertheless, can manage to feed; and if some are even wanting, the animal can subsist. A few would serve to grasp a sufficiency of food, especially such food as the state of the mouth, during the period of dentition, would dispose the colt to partake of. The animal is then in an inflammatory condition--the system is excited--and it is a wise provision which leaves the creature inclined only, at such a time, to consume a soft and laxative herbage, not in too great a quantity. The molars, on the contrary, if irregular in their growth, or uneven upon their surfaces for any lengthened period, would produce great local pain, and much constitutional disturbance.