1868.] DENTITION OF THE ARMADILLOS. 379 



I will describe the specimens examined in the order of their re- 

 spective 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 foetal specimen, of which the head was 1""C, 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 depres- 

 sions, quite clean. They were all in nearly the same stage of deve- 

 lopment ; 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 G", and the 

 tail 6i" 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 com- 

 pressed, 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 3j", 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 com- 

 pressed 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 speci- 

 men, were the germs of the second or permanent teeth. 



