LAGOMYID.Z. 255 
Suborder RODENTIA DUPLICIDENTATA. 
Incisors 2, at birth = ; the outer upper incisors soon lost; the next 
pair very small, and placed directly behind the large middle pair. 
Family LAGOMYIDAL. 
Genus LAGOMYS, Cuvier’. 
Syn. Titanomys, H. v. Meyer’. 
Amplulagus, Pomel ®. 
Myolagus, Hensel *. 
Dentition:—In the existing species the formula of the cheek- 
dentition is Pm. = M. S 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 72tanomys (but including Amphilagus), the 
penultimate premolar is normally wanting in both jaws. As there 
is such a gradual and complete transition from the typical Lagomys 
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. 
Lagonuws pustllug (Pallas ’). 
Syn. Lepus pusillus, Pallas °. 
Lagomys speleus, Owen". 
The so-called L. speleus, 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. 
Hab. 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 speleus, of which it is the 
type. McEnery Collection. Purchased, 1842. 
1 Tabl. Hlém. d. Hist. Nat. p. 182 (1798). 
2 Neues Jahrb. 1843, p. 393. 
3 Catalogue Méthodique, p. 42 (1853). 
4 Zeitschr. deutsch. geol. Ges. vol. viii. p. 688 (1856). 
° Nov. Comm. Petrop. vol. xiii. p. 531 (before 1778), Lepus. 8 Loe. cit. 
* British Fossil Mammals and Birds, p. 213 (1846). 
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