114 Miller — Note on tJie Milk Dentition of Desniodas. 



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

 tlie ti})s of tlie latter remain for a considerable period tne most 

 cons|)icuoas teeth in either jaw. Their strongly recurved tips 

 are probably of great service to the 3'oung when clinging to the 

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

 ous incisor lies on tlie 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 graduall}^ extends backward until both 

 milk incisors a[)pear 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 ^irominence caused by 

 tlie growing permanent canine. It 

 is shed at an early age, and never 

 l)ecomes in any way functional. A 

 deciduous molar (Fig. 1, h, dm) was 

 found occup3'ing a position near 

 FIG 2.-Maudibuiar teeth of /;...«<,- ^j^^ posterior outcr bordcr of the 



(IHS i-u/its, snowing part of milk den- ^ 



titiou (a) and gradual change in form fii'st permanent Upper premolar in 

 toaduit (c) ( / 5). two specimeus. 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. 52180) 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 

 mandi])ular canine closel}' 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, dl) are very small and loosely attached to the gum 

 through which they scarcely ]iierce before they are shed. In 

 form they are totally diflFerent from the corresponding upper 

 teeth. Their ti})s are somewhat widened and faintly notched, 

 thus suggesting the form presented by the permanent lower 

 incisors of many bats. 



