KEY TO GENERA 95 



Skull with the temporal ridges widely 

 separated in the interorbital region; post- 

 orbital crests of squamosals weak ; braincase 

 smooth, depressed, and delicately built. 

 Auditory bullae well inflated, with spongy 

 tissue within. 



Fur soft, dense, and more or less mole-like. 

 Eyes and ears small, the latter concealed. 

 Soles moderately hairy ; plantar tubercles 5 ; 

 claws shghtly lengthened. Tail short. 



Pitymys. 

 *. Mammae 0—2 = 4. . . Subgenus Pitymys. 

 **. Mammae 1 — 2=6. . Subgenus Micrurus. 

 p. Cranial and external characters not specially 

 modified for fossorial life. 



Skull with the temporal ridges fused in 

 the interorbital region when adult; post- 

 orbital crests moderate; squamosals tend- 

 ing to approach each other anteriorly with 

 advancing age. 

 *. Skull with facial portion not unusually 

 elongate; palate normal. Auditory bullae 

 strengthened by net of bony trabeculae 

 within, 

 f. Braincase not specially deep and sub- 

 cyHndrical. Auditory bullae moderately 

 large; mastoid portion not noticeably 

 inflated. 



Fur soft and full. Ears evident above 

 the fur. Claws of hands and feet 

 rather long, subequal ; soles not densely 

 hairy; plantar pads usually 6, but 

 sometimes reduced to 5. Tail rather 

 long, from one-third to half the length 

 of the head and body. Mammae 



2—2=8 Neodon. 



■ff. Braincase deep and subcyHndrical. Audi- 

 tory bullae small; mastoid portion 

 inflated. 



Fur long and coarse. Ears small, con- 

 cealed in fur. Hands and feet broad; 

 hind-claws slightly longer than fore- 

 claws ; soles hairy ; plantar tubercles 5. 

 Tail shorter, rather less than one-third 

 the length of the head and body. 

 Mammaj 1 — 2=6 . . . . Pedomys. 

 **. Skull with facial portion unusually elongate; 

 palate with deep and extensive postero- 

 lateral pits and very long and narrow 

 postero-median septum. Auditory bullae 



small t Tyrrhenicola. 



, nil usually with five or more closed triangles, 



never less than four ; the fourth triangle never 



confluent with the fifth. 



o. Vestiges of " intermediate tubercles " (" pro- 



toconule," " metaconule," etc.) normally 



