LAGOMYID.E. 255 



Suborder RODENTIA DUPLICIDENTATA. 



Incisors |, at birth | ; the outer upper incisors soon lost ; the next 

 pair very small, and placed directly behind the large middle pair. 



Family LAGOMYID^). 



Genus LAGOMYS, Cuvier 1 . 

 Syn. Titanomys, H. v. Meyer 2 . 

 Amphilagus, Pomel 3 . 

 Myolagus, Hensel 4 . 



Dentition: In the existing species the formula of the cheek- 

 dentition is Pm. |, M. |. In certain fossil forms, however, to which 

 Pomel (loc. cit.) gave the name Amphilagus, the penultimate lower 

 premolar is very minute ; while in others, for which Hensel has 

 proposed the name Myolagus, it is wanting. In another group, 

 forming Meyer's genus Titanomys (but including Amphilagus), the 

 penultimate premolar is normally wanting in both jaws. As there 

 is such a gradual and complete transition from the typical Layomys 

 to the so-called Titanomys, it seems inadvisable to retain the three 

 genera Lagomys, Myolagus, and Titanomys ; and all the forms are 

 accordingly grouped under the type genus. It is remarkable that 

 it is the newer forms which retain the penultimate premolar. 



pujStltuS (Pallas 5 ). 



Syn. Lepus pusillus, Pallas 6 . 

 Lagomys spelceus, Owen '. 



The so-called L. spelazus, Owen, is considered by Sanford (Quart. 

 Journ. Geol. Soc. vol. xxvi. p. 126) to be in all probability identical 

 with the existing Siberian L. pusillus. The penultimate premolar 

 is minute. 



Hob. N. Asia and Europe. 



48886. Anterior portion of the cranium, showing the incisors and 

 (Fig.) most of the cheek-teeth; from Kent's Hole Cavern, Tor- 

 quay. This specimen is described and figured by Owen 

 in the Brit. Foss. Mamm. and Birds, p. 213, figs. 82-4, 

 under the name of Lagomys spelceus, of which it is the 

 type. McEnery Collection. Purchased, 1842. 



1 Tabl. Blem. d. Hist. Nat. p. 132 (1798). 



2 Neues Jalirb. 1843, p. 393. 



3 Catalogue Methodique, p. 42 (1853). 



4 Zeitschr. deutsch. geol. Ges. vol. viii. p. 688 (1856). 



5 Nov. Cornm. Petrop. vol. xiii. p. 531 (before 1778), Lqptu. 6 Loc. cit. 

 ' British Fossil Mammals and Birds, p. 213 (1846). 



