582 Bulletin American Museum of Natural History. [Vol. XXIV, 



total length, 17 (in tropidorhynchus, 15); width of brain case, 9 (in tropi- 

 dorhynchus, 8). The skull is more massive, the rostral portion especially 

 more thickened, the brain case more expanded, and the dentition throughout 

 notably heavier; the lower jaw is markedly deeper and heavier, and the 

 canines in both jaws are nearly twice as large as in tropidorhynchus. 

 Represented only by the type. 



III. NOTE ON THE TYPE OF THE GENUS SCITJROPTERUS. 



The genus Sciuropterus F. Cuvier was first defined under the vernacular 

 name Sciuroptere by F. Cuvier in 1823 (Mem. du Mus., X, 1823, p. 126), 

 and based on "le sciuroptere assapan (sciurus volans Lin.), qui me servira 

 d'object de comparaison avec le pteromys taguan, . . . " The first use of 

 Sciuropterus is by the same author in his 'Dents des Mammiferes,' in the 

 ' table methodique,' p. 255, where is given "Sciuropteres, Sciuropterus F. 

 Cuv. Sciuroptere polatouche, sciurus volans Linn." 



Regarding the ' assapan' of F. Cuvier, the original type of his Sciurop- 

 terus, he says ('Hist. Nat. des Mammiferes, livr. viii, July 1819): "C'est 

 sous le nom impropre de polatouche que Buffon a parle de cet animal, 

 originaire de I'Amerique septentrionale, tandis que le polatouche, propre- 

 ment dit, est du nord de Pancien continent, et que c'est des Russes qu'il a 

 re9u ce nom, ou plut6t celui de polatouka." This is important, inasmuch 

 as Sciurus volans Linn, includes both the assapan and the polatouche, 

 while M us volans Linn., on an earlier page of the same work (cf. Syst. Nat., 

 ed. 10, 1758, pp. 85 and 88), relates exclusively to the assapan. 



Mr. Oldfield Thomas, in a recent paper entitled 'The Genera and Sub- 

 genera of the Sciuropterus Group, with descriptions of three new Species' 

 (Ann. and Mag. Nat. Hist. (8), I, pp. 1-8, Jan. 1908) has, with apparently 

 good reason, divided the group into six genera (Trogopterus Major, Sciurop- 

 terus F. Cuv., and lomys, Belomys, Pteromyscus and Petaurillus, genn. nov). 

 He has also separated his Sciuropterus sens, stric. into four subgenera, of 

 which three are new, namely: Sciuropterus, Glaucomys, Hylopetes, and 

 Petinomys, and designated a type for each. The type of Glaucomys is 

 unfortunately given as " Sciuropterus (Glaucomys) volans (Mus volans 

 Linn.)," which is F. Cuvier's "sciuroptere assapan," the monotypic type of 

 his genus Sciuroptere (later his Sciuropterus). 



Sciurus volans Linn, was, as said above, composite; although based 

 primarily on No. 22, Fauna Suec. (1746), which relates exclusively to the 

 European flying squirrel ("Habitat in Finlandia & Lapponia"), it also 

 included the North American flying squirrels as described and figured by 



