114 Miller Note on the Milk Dentition of Desnwdus. 



permanent incisors (Fig. 1, i), and even after the appearance of 

 the tips of the latter remain for a considerable period tiie most 

 conspicuous teeth in either jaw. Their strongly recurved tips 

 are probably of great service to the young when clinging to the 

 nipple of the female during flight. At first the anterior decidu 

 ous incisor lies on the outer side of the permanent incisor, while 

 the posterior deciduous incisor occupies the space between the 

 permanent incisor and canine (Fig. 1, a). As the permanent 

 incisor increases in size, it gradually extends backward until both 

 milk incisors appear closely appressed to its outer face. In this 



condition (Fig. 1, c) the teeth re 

 main until the animal acquires a 

 large size, while the second milk 

 incisor often persists in nearly full- 

 grown individuals (Fig. 1, d). The 

 deciduous canine (Fig. 1, a. dc) lies 

 imbedded in the gum on the outer 

 side of the prominence caused by 

 the growing permanent canine. It 

 is shed at an early age, and never 

 becomes in any way functional. A 

 deciduous molar (Fig. 1, b, dm} was 

 found occupying a position near 

 FIG 2.-Mandibuiar teeth of Desmo- ^ posterior outer border of the 



aus riifus, showing part or milk den 

 tition (a) and gradual chang* in form first permanent upper prcmolar in 



to adult (ocx 5). two specimens. This tooth lacks 



the recurved tip and must be wholly functionless. 



In the lower jaw (Fig. 2) the deciduous teeth are smaller and 

 less conspicuous than those in the upper jaw. They are also 

 shed at a much earlier period. On opening the mouth of one 

 specimen (No. 52130) I found two deciduous molars lying loose 

 on the gum over the permanent premolars. The exact position 

 of these milk teeth could not be determined, and I failed to 

 detect any trace of them in other individuals. The deciduous 

 mandibular canine closely resembles its counterpart in the upper 

 jaw, both in size, position, and history. Its tip is, however, less 

 strongly hooked (Fig. 2, dc). The deciduous lower incisors 

 (Fig. 2, di) are very small and loosely attached to the gum 

 through which they scarcely pierce before they are shed. In 

 form they are totally different from the corresponding upper 

 teeth. Their tips are somewhat widened and faintly notched, 

 thus suggesting the form presented by the permanent lower 

 incisors of many bats. 



