12 PROCBEDTNOS OF THE NATIONAL MUSEUM. vol.45. 



dental characters. Jentink ^ gives the vertebral formula D. 14, L. 5, 

 S. 3, Cd. 31. He further says: ''The ribs are peculiarly broad. The 

 cla-sdcle is Well developed ; the bones of the forearms and of the hind 

 legs are separate." 



TEETH. 



The dental formula of the Tupaiidse is /. §, C. |^, Pm |, M. f. 

 The teeth are typically insectivorous and nearly represent the full 

 possible Eutherian dentition; one upper incisor is lacking, and one 

 upper and one lower premolar. As to which of the theoretical teeth 

 are lacking does not seem to me to be a matter of great importance. 



My own view of the formula is 7. y^ , C. jP- z^W2^ , M. -r^-g • The 



reason for considering that the third upper mcisor is wanting and 

 not the first is that the third lower incisor is a vanishing tooth and 

 has almost disappeared in Urogale. This opinion is the same as that 

 of Gregory.^ He thinks that in Ptilocercus i^ is lacking and is 

 represented by a minute alveolus. The only reason for assuming 

 P \ are wanting is that at present the most anterior premolar is the 

 smallest of the series, and it seems not unreasonable to assume that 

 at one time it may have had standing in front of it a still smaller 

 tooth; furthermore, all of the premolars are preceded by milk teeth 

 which is usually not the case with the first premolars. 



The canines in the family are mteresting in that they do not have 

 the form and functions of true canines, but are almost indistinguish- 

 able from the premolars. It might with some degree of propriety 

 be said that the ideal number of premolars is present in the family 

 and that the canines are lacking, especially since the canine in Ptilo- 

 cercus and occasionally in the other genera is tWo-rooted, not a charac- 

 ter of canine teeth, and since the canine is situated considerably 

 posterior to the premaxillo-maxillary suture, rather than in or almost 

 in that suture, as in most other mammals. The only exception to 

 this is in Urogale where the lower canine has the form and function 

 of a true canine, and although the second upper incisor functions as 

 a canine, yet the canine itself is more caniniform and less premolari- 

 form than is the case in the other genera. The canmes are always 

 preceded by milk canines. • 



For the shape and arrangement of cusps, etc., of the teeth figures 

 on pages 33, 121, 128, 135, 155, and 161 should be consulted. Differ- 

 ences that are useful for purposes of classification will be discussed 

 under each genus. 



Eruption of teeth in Tupaiinse. — The manner and order of eruption 

 of teeth in the subfamily Tupaiinae shows nothing not commonly seen 



1 Notes Leyden Museum, vol. 7, 1885, p. 38. 



2 Bull. Amer. Mus. Nat. Hist., vol. 27, 1910, p. 271. 



