1876.] MR. E. R. ALSTON ON THE ORDER GLIRES. 9/ 



3. 0y</roc/*(ErMS, Brisson, R6gn. An. p. 1 16 (1756). 



Body massive ; limbs moderate ; muzzle very blunt ; eyes and ears 

 small; tail obsolete ; hair coarse and sparse; all the feet fully webbed. 

 Skull massive ; malar very deep ; palate produced behind the last 

 molar ; incisive foramina short ; paroccipital processes very large and 

 long. Upper incisors grooved in front ; upper grinding-teeth each 

 with two lobes, united only by cement, except the third molar, which 

 has twelve narrow transverse plates ; lower premolar and first molar 

 with three narrow lobes, the second and third with four. 



Suborder II. Glires duplicidentati. 

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

 pair very sniall, placed directly behind the large middle pair ; their 

 enamel continuous round the tooth, but much tliinner behind. Skull 

 with the optic foramina confluent, with no true alisphenoid canal ; 

 incisive foramina usually confluent ; bony palate reduced to a bridge 

 between the alveolar borders. Fibula ankylosed to tibia below, and 

 articulating with the calcaneum. Testes permanently external; no 

 vesicular glands. Two families : — 



Family I. Lagomyid^. 



Either one or two premolars above and below ; grinding-teeth 

 rootless, with transverse enamel-folds dividing them into lobes. Skull 

 depressed ; frontals contracted, with no postorbital processes ; facial 

 surface of maxillary with a single perforation ; posterior an^le of 

 malar produced almost to the auditory meatus ; basisphenoid not 

 perforate, nor separated by a fissure from the vomer ; coronoid pro- 

 cess in the form of a tubercle. Clavicles complete. Ears short. Hind 

 limbs not markedly elongated. No external tail. Palsearctic and 

 Nearctic. Recent genus : — 



1. Lagomys, G. Cuvier, Tabl. El em. de I'Hist. Nat. p. 132 (1798). 



External characters those of the family ; two premolars above and 

 below. 



Fossil genus : — 



2. Titanomys, Von Meyer, Jahrb. fiir Mineralog. 1843, p. 393 



(1834). 

 One premolar only, both above and below. 



Family II. Leporid^. 

 Three premolars above, and two below ; grinding-teeth as in last 

 family. Skull compressed; frontals with large wing-shaped post- 

 orbital processes ; facial portion of maxillaries minutely reticulated ; 

 basisphenoid with a median perforation and separated by a fissure 

 from the vomer ; coronoid process represented by a thin ridge of bone. 

 Clavicles imperfect. Ears and hind limbs elongated. Tail short, 

 bushy, recurved. Cosmopolitan (except Australasian region). Re- 

 cent genus : — 



Proc. ZooL. Soc— -1876, No, VII. 7 



