94 MR. E. R. ALSTON ON THE ORDER GLIRES. [Jail. 18, 



digits; the hind feet with a nailless tubercle instead of the first digit, 

 and an internal lobe, supported by two accessory tarsal ossicles. 

 Skull short ; the frontal and malar with large postorbital process, 

 which almost meet ; walls of auditory meatus produced. Upper 

 grinding- teeth each divided into three lobes, of which the anterior 

 and posterior have deep single enamel-folds ; lower teeth with one 

 external and two internal folds. 



2. Sphingxirus { = Sphig gurus), F. Cuvier, Dents d. Mamm. p. 256 



(1825)*. 



Nostrils far apart ; head and body clad above with short stiff spines, 

 or with mixed spines and bristly hair ; feet as in Chcetomys ; tail 

 long, prehensile at its tip. Skull short ; the air-sinuses greatly 

 developed in some species ; no postorbital processes; walls of auditory 

 meatus not produced ; interparietal broad ; angle of mandible pointed. 

 Grinding-teeth subequal, like those of Sjihiugvrus, but with two 

 lobes only. 



3. Erythizon, F. Cuvier, Dents d. Mamm. p. 256 ... (1825). 



External characters as in Sphingurus, but the nostrils nearer to- 

 gether, the quills more concealed by hair, the hind feet with five toes 

 and hardly any internal lobe ; the tail short, thick, and non-prehen- 

 sile. Skull with walls of auditory meatus slightly produced ; angle 

 of mandible rounded. Grinding-teeth like those of Sp>hingurus, but 

 the anterior much longer than the posterior. 



B. Hystricin^e. Grinding-teeth semirooted. Skull more elon- 

 gate ; lachrymal partly bounding the canal. Clavicles imperfect. 

 Upper lip furrowed ; tail not prehensile ; soles of feet smooth ; six 

 teats. Palaearctic, Indian, and Ethiopian. Recent genera : — 



4. Atherura, G. Cuvier, Regne Animal (2 me e'd.), i. p. 215 (1829). 



Spines flattened, channelled ; tail long, scaly, with a tuft of com- 

 pressed bristles at the point. Nasal part of skull moderate. Upper 

 grinding-teeth with one internal and three or four external folds, the 

 latter soon separated as enamel-loops ; the lower teeth similar, but 

 reversed. 



5. Hystrix, Linnaeus, Syst. Nat. i. p. 76 (1/66). 



Spines cylindrical ; tail short, covered with spines and slender- 

 stalked open quills. Nasal cavity usually very large. Air-sinuses of 

 frontals greatly developed. Teeth as in Atherura. 



Family III. ChinchileiDjE. 



Incisors short ; grinding-teeth divided by continuous folds into 

 transverse laminae. Malar extending forward to lachrymal, with no 

 inferior angle, and only a rudimentary superior angle. Optic fora- 

 mina confluent. Auditory bullae moderate or very large. Palate con- 

 tracted in front, and deeply emarginate behind. Clavicles perfect. 



* — Syndhcres and Sj^higgitrus, F. Cuvier (1825)= CcrcoJabcs, Brandt (1835). 



