1893.] DB. C. J. rOESYTH MAJOR OIT 3II0CEKE SQUIRRELS. 179 



1. On some Mioceue Squirrels, with Remarks on the Den- 

 tition and Classification of the Sciurinee. By Dr. C. J. 

 Forsyth Major, C.M.Z.S. 



[Received February 14, 1893.] 



(Plates VIII.-XI.) 



I. Introduction, p. 179. 

 II. On the Dentitiou of the Sclurina, p. 179. 



III. Remarks on the Classification of the Sciurida;, p. 186. 



IV. Description of the FossQ Species, p. 190. 



V. On the primitive Tji^e of the Sciurine Molar, and of the 

 Eiitherian Molar in general, p. 196. 

 YI. Explanation of the Plates, p. 214. 



I. Introduction. 



In order to determine some remains of Squirrels, collected by 

 myself in the IMiddle-Mioceue deposits of La Grive-Saiut-Albau 

 (Iscre), it was necessary to compare them witli their actual con- 

 geners. I have to thank botli l)r. A. Giinther and Mr. Oldfield 

 Thomas for the kindness shown to me in permitting a close exami- 

 nation of the rich collection of JSciurine skulls in the Zoological 

 Department of the British Museum ; and I am besides under great 

 obligations to Mr. Thomas, who is so thoroughly ac(|uainted not 

 only Nvdth eA'ery species, but indeed with e^•evy specimen of the 

 collection under his charge, for ha\ing liberally favoured me with 

 his experience and advice, especially in regard to intricate ques- 

 tions of synonymy and specific determination. 



The investigation of living fonns has led me somewhat farther 

 than I had anticipated ; so that before treating of the fe\\' fossil 

 remains, it will be necessary to pass in review the numerous, and, 

 in several instances, very unexpected forms of Sciurine dentition, 

 as Avell as to present some i-emarks on their classification. 



The brachydont teeth of Sciurinee presenting a ^ery primitive 

 type of Eodent molars, I ^\as naturally led to consider them in 

 the light of the preA'ailing theory, the so-called tritubercularity, 

 the rodent molars having been traced, as those of other orders, to a 

 trituberculate type. This forms the subject of the last part of my 

 communication. 



II. On the Dentition of the Sciurinae. 



It is a well-known fact that in various famiUes of the Rodent ia 

 tubercular molars — which as a rule are brachydont — and laminated 

 molars — which as a rule are hypsodont or rootless — are met 

 with side by side in closely allied genera and in existing species, 

 whilst in some other Orders we have to look among fossils for 

 the more or less brachydont precursors of the living hypsodont 

 forms. 



It is equally well know^n, though not always called to mind, 



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