492 Dr. C. I. Forsyth Major — On Fossil Dormice. 



III. — On Fossil Dormice. 

 By Dr. C. I. Forsyth Major, F.Z.S. 



IN the nomenclatui'e of fossil Myoxidge, the generic terra Myoxus has 

 hitherto been used in a broad sense, under the assumption that 

 the distinctive characters of the recent genera of the family are not 

 apparent in their Tertiary representatives. It is my purpose to show 

 in the present note that this is not the case, there being in the 

 Middle Miocene, at any rate, two forms of Myoxidse, one a Muscar- 

 diniis, the other an EUomys, which have been mixed up together by 

 several previous writers, under the name Myoxus Scmsaniensis. 



1. MuscARDiNUS Sansaniensis (Lartet). 

 Myoxus Sansaniensis, Lartet: Notice Colline de Sansan, 1851, p. 20. 

 P. Gervais: Zool. Pah Fr., 2^ ed. (1859), p. 37, pi. xliv, 

 figs. 14-19. Lydekker : Cat. Foss. Mamm. Brit. Mus., 

 part i (1885), p. 224. H. Filhol : Ann. Sc. GeoL, xxi 

 (1891), 1, p. 39, pi. i, figs. 9, 10. ? Deperet : Arch. Mus. 

 Lyon, V (1892), p. 61. 

 ? Myoxus niteloides, Deperet : Arch. Mus. Lyon, iv (1887), p. 154, 



pi. xiii, figs. 15, 15a. 

 Myoxus Zitteli, Hofmann : Abh. k. k. Geol. Eeichsanst., xv (1893), 

 6, p. 43, pi. iii, figs. 15, 16. 

 As regards the shape and relative proportions of its cheek-teeth, 

 the recent Muscardinus avellanarius^ is more specialized than either 

 EUomys or even Glis [Myoxus). The premolar is more reduced than 

 in the latter two genera, owing to its being interi'ered with by the 

 incisor;^ apparently by way of compensation, the first true molar is 

 increased in length. Moreover, the triturating surface of the molars 

 of Muscardinus exhibits the shape of a rasp much more pronounced 

 than in the above-mentioned two genera. This conformation is 

 quite unique amongst mammalian teeth ; the molars of Eiephas have 

 been compared with those of Muscardinus, but they are hypselodont 

 in the extreme and exhibit on their crown an alternation of layers of 

 enamel, dentine, and cementum, whereas those of the latter genus 

 are probably the most brachyodont of all mammalian teeth. 



We might expect that fossil members of the genus will show 

 a more normal condition of their teeth than Muscardinus avellanarius ; 

 this is, in fact, in one respect realized in the left upper jaw of 

 a dormouse, which more closely approaches to Muscardinus than to 

 either EUomys or GUs, and which 1 therefore consider as a species 

 of the former genus. I collected it some years ago in the Middle 



1 It is almost generally admitted that the genus is represented by only one recent 

 species. However, the Italian Muscardinus rejoices in two specific names: Myoxiis 

 speciosus, Dehne, from Tursi in the Basilicata, Southern Italy (Allg. deutsche natur- 

 hist. Zeit., 1865, p. 180) ; and Aluscardmus pulcher, Barrett-Hamilton, from Siena 

 in Tuscany, Central Italy (Ann. Mag. Nat. Hist. (7), ii, 1898, p. 424). I have 

 examined the skull and dentition of the type of M. pulcher, and cannot find the 

 slightest diflierence from Northern specimens. On ' Mijoxus speciosus' see Blasius, 

 Naturg. Saugeth. Deutschl., 1857, p. 298. 



■•* Winge, "Dm grajske Pattedyr": Vidensk. Meddel. Naturh. Foren. Kjbben- 

 havnf. Aaret, 1881, p. 52 (1882). 



