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. Sphingurus {=^Sphiy gurus), F. Cuvier, Dents d. Manim. 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. 

 fj.p A-j^iA / Grinding-teeth subequal, like those of SpJmtffttrtfs, but with two 



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 Sphmgurus,h\\i 

 the anterior much longer than the posterior. 



B. HystriciNjE. 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. Palsearctic, Indian, and Ethiopian. Recent genera : — 



4. Atherura, G. Cuvier, Eegne Animal (2m<'cd.), 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, tiie 

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

 reversed. 



5. Hystrix, Linnaeus, Syst. Nat. i. p. 76 (1766). 



Spines cylindrical ; tail short, covered with sj)ines and slender- 

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

 frontals greatly developed. Teeth as in Atherura. 



Family III. Chinchillid^. 



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 cmargiuate behind. Clavicles perfect. 



* =Syncthcrcs aud f'fhiggv.nis, F. Cuvier (1826)= Cercolabes, Brandt (1835). 



