2888,] 0. Thomas — Eupetaurus, a neiv form of Flying Squirrel. 259 



palate, lenf^fcli 41, breadth including posterior premolars 20'8, least 

 breadth inside the same teeth 6" 7 ; diastema, length, 16'8 ; anterior 

 palatine foramen (c) 8' 5 ; length of molar series, from front of last 

 premolar to back of last molar, i9"3. Lower jaw, length (bone only) 54" 5, 

 (to incisor tip) 59, height, from condyle to below angle, 34*6. 



The discovery of such a fine new mammal as tlie present in so com- 

 paratively well-known a region as Kashmir, is very remarkable, and 

 especially as Eupetaurus is found in Gilgit, a place whose fauna Dr, John 

 Scully, both as collector and describer,* has so thoroughly and ably 

 investigated. 



It was under the skilled supervision of Prof. Wood-Mason that 

 Behari Lai Das executed the beautiful drawing of its skull now re- 

 produced to form Plate XXIII. 



A further interest, however, attaches to JEl iipetaurus from its being 

 the only member of the Sciuridce in which the character of hypsodon- 

 tismf has been developed, although, among the whole group of Sciuro- 

 morpha. Castor and Anomaluriis have hypsodont teeth, while Haplodon 

 has the still further advance of possessing permanently rootless molars. 

 Throughout mammals hypsodontism has been developed independently 

 over and over again, as for example in Elephas as compared to the braohyo- 

 dont Mastodon; in Equus as compared to Anchitherinni, in Neotoma as 

 compared to Gricetus, and, best known of all, in the Bovidce as compared 

 to the Gervidcd. 



The superiority of high-crowned over low-crowned teeth is obvious, 

 especially to animals living on food that has a strong grinding action on 

 the teeth due either to natural silex contained in it, or to sand and 

 dirt mixed with it. In all cases it is probable that the jaws have a more 

 or less horizontal chewing action in hypsodont, as compared to a vertical 

 *' chumping " action in brachyodont animals. 



Finally it should be noticed that hypsodontism represents of course 

 only the first step towards the development of entirely rootless teeth, a 

 development that has again often independently taken place, but which 

 must in every case have been by way of hypsodontism, the complete 

 series of steps being evidently as follows. First and least specialized then 

 is the short-crowned long-rooted tooth (as in ordinary brachyodont 

 animals) ; secondly, the high-crowned short-rooted tooth (as in the hypso- 



* Cf. " On the Mammals of Gilgit, p. 35, 1881, p. 197, and " On some Mammals 

 ^rom the North-West frontier of Kashmir," Ann. Mag. N. H. (5) VIII, p. 95, 1881. 

 I understand that Dr. Scully himself recogTiised Mr. Giles's Flying Squirrel as new. 



t A concise description of hypsodontism lias been given by Flower, Encycl. 

 Brit. (9) Art. Mammalia, XV, p. 471, 1883. 

 34 



