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Show 1868.] DENTITION O F T H E A R M A D I L L O S . 379 I will describe the specimens examined in the order of their respective ages. The first three are preserved in spirit in the Museum of the Royal College of Surgeons; the fourth is a skeleton in the British Museum. 1. In a fcetal specimen, of which the head was 1"*6, the body 3", and the tail 2"*7 long, there was no appearance of teeth above the gums ; on each side of the mandible and of the corresponding part of the maxilla were the germs of seven teeth, each consisting of a soft papilla, enclosed in a round follicle. On stripping up the mucous membrane covering the edge of the jaw, they all came away attached to it, leaving the dental groove, with seven distinct alveolar depressions, quite clean. They were all in nearly the same stage of development ; but those in the middle were rather larger than those at either extremity of the series. The length of the row of teeth above and below was almost exactly the same, viz. 0"*32. 2. In the next specimen the head was 2|", the body 6", and the tail 6|" long. In the upper jaw, on each side, the apices of five teeth were just appearing above the mucous membrane; beneath the membrane, behind these, were the calcified germs of two others, making seven in all. They were all mere caps of calcareous matter, widely open below, their height scarcely exceeding their width at the base; the apices were rounded, the first simple and compressed, the second slightly wider but also simple, all the others double the width of the first, and divided by a longitudinal groove into an inner and an outer cusp, of which the inner was rather the larger. The entire tooth-row was 0"*55 long. The lower jaw had also seven teeth on each side in a corresponding state of development-the first very small and single-pointed, all the others with a bicuspid apex, the inner cusp being higher and more pointed than the outer. On the left side, 0"*1 in front of the first of these teeth, was a minute calcified tooth scarcely larger than a blunt pin's point. I could not find one corresponding to it on the other side, or in the upper jaw, or in any of the other specimens examined ; so its presence may have been an individual peculiarity. The other teeth were all in close apposition to one another. 3. In the third animal the head was 3|", the body 8", and the tail 10" long. In the upper jaw there were seven teeth on each side, the points of all of which had cut the gum, but were quite unworn ; and there was a minute uncalcified germ of the eighth in a distinct alveolar socket close behind the seventh. All, except the much compressed first had bilobed crowns (the divisions being not very distinct in the second). In the teeth about the middle of the series, which were the largest, the calcified portion was 0"* 15 long, quite simple, open, but rather contracted at the base. The tooth-line was 0"*75 long. The lower jaw showed a precisely corresponding condition. Rather below the middle of the inner wall of the alveolar cavities, most conspicuous in the lower jaw, were distinct little pits filled with a soft substance. These, as shown by the examination of the next specimen, were the germs of tbe second or permanent teeth. |