1876.] MR. E. R. ALSTON ON THK ORDER GLIRES. 83 



sparsely haired. Cheek-pouclies large. Skull most like that of 

 Saccostomus, but incisive foramina much smaller. Upper incisors 

 grooved. Molars as in Saccostomus. 



H. Murine. Molars tuberculate, at least in youth. Infraorbital 

 opening typical ; pterygoid fossae lengthened ; auditory bullae mode- 

 rate. Cheek-pouches absent or very small. Tail scaly, more or 

 less naked. Cosmopolitan. Recent genera : — 



16. 3Iits, Linnseus, Syst. Nat. i. p. 79 (1766). 



Muzzle pointed ; eyes prominent ; ears rather large, subnaked ; fur 



soft (rarely mixed with spines); pollex rudimentary; claws short; tail 

 moderate or long, scaly, with scattered hairs. No cheek-pouches. 

 Skull elongate, narrow ; temporal ridges nearly parallel ; palate com- 

 pressed ; incisive foramina long ; auditory bullce moderately large ; 

 coronoid process high, falcate. Incisors rarely grooved. Molars 

 with transverse ridges, each composed in youth of three tubercles. 



17. Pelomys, Peters, Reise n. Mossambique, i. p. 157 . (1852). 

 Middle three digits of each foot longer than the first and third ; 



fur bristly ; tail short, scaly. Palate much compressed. Incisors 

 grooved. Molars broader than in Mus. 



18. Echinothrix {=Echiothrix), Gray, P. Z. S. 1 807, p. 599(1867). 

 Head elongate, muzzle produced ; fur mixed with flattened spines ; 



tail long, scaly. Facial portion of skull greatly elongated ; nasals 

 very narrow ; palate much compressed ; incisive foramina long; coro- 

 noid process small. Incisors grooved. First upper molars large, with 

 three ridges, second with one only ; third small, simple, subcircular. 



19. Vrcmys, Peters, Monatsb. Ak. Berlin, 1867, p. 343 (1867). 



External cliaracters as in Mvs ; but the caudal scales thick, poly- 

 gonal, and not overlapping, auditory bullse and incisive foramina 

 smaller, and ])terygoid processes more like those of Hapalotis. 



20. Hapalotis, Lichtenstein, Darst. neu. Saugeth. Th. iv. pi. 29 



(1829). 

 Muzzle produced ; ears long, tapered, sparsely haired outside ; hind 

 limbs elongated ; fur soft ; tail long, hairy, terminating in a pencil. 

 Skull with no distinct occipital crest or supraorbital ridges ; incisive 

 foramina very large; coronoid process obsolete. Incisors plain. 

 Molars as in Mus. 



21. Acomys, Is. GcofTroy, Ann. Sc. Nat. 2»e g^r.x. p. 126 (1840). 



Fur mixed with flattened spines, especially on the head and back ; 

 tail short, scaly. Skull as in Mxis, but the pterygoid fossae more 

 shallow, and the incisive foramina extremely small ; coronoid process 

 little developed. Teeth as in Mus. 



22. iViesoOT?/*, Peters, Sitzungs-Ber.Gesell. nat. Freunde, 1870, p. 54 



(1871). 

 Form murine ; uj)per lip grooved, not cleft ; ears and eyes large ; 



G* 



