18C8.] DR. J. E. GRAY ON SACCOMYINiE. 201 



hind feet, D. philHpsii, and one with a shorter tail and slenderer fore 

 feet, D. ordii, with different geographical distribution (see M. N. 

 Amer. pp. 409,414, 415). 



2. DiPODOMYS ORDII, Woodhouse, Leconte, Proc. Acad. N. S. 

 Philad. vi. 1853, p. 224 ; Spencer Baird, Mamm. N. A, 410, t. 21. 

 f. 1, t. 31. f. 1, 2 (skull). 



?D. tnontanus, Spencer Baird. 



3. DiPODOMYS AGiLis, Gambcl, Proc. Acad. N. S. Philad. iv. 

 1848, p. 77 ; Spencer Baird, Mamm. N. A. 414. 



4. DiPODOMYS HERMANNii, Lccontc, Proc. A. N. S. Philad, vi. 

 1853, p. 224. 



Hab. Sierra Nevada. 



5. DiPODOMYS wAGNERi, Leconte, Proc. A. N. S. Philad. vi. 1853, 

 p. 224. 



Hab. South Carolina. 



2. Grindeis rooted. Heteromyiua. 

 f Upper cutting-teeth with a longitudinal groove. 



2. Perognathus. 



Perognathus, Pr, Max. Nova Acta Acad. C. L. C. xix. 369, 1839 ; 

 Spencer Baird, Mamm. N. A. 416. 



Cutting-teeth with a longitudinal groove. Fur spinous or bristly ; 

 spines flat, with a central channel on the upper surface. Ears 

 rather large, with a distant suborbicular lobe to the antitragus. 

 Sole of the hind feet naked to the heel. Tail covered with dense 

 hairs, sometimes tufted at the tip. 



1. Perognathus penicillatus, Woodhouse, Pr. Acad. N. S. 

 Philad. vi. 200, 1852 ; S. Baird, Mamm. N. A. 418, t. 20. f. 5 ; Sit- 

 graves, Expl. Colorado, 49, t. 3, 1853; Aud. & Bach. N. A. Quad, 

 iii. 298, 1854. 



Junior? P. parvus, Spencer Baird, M. N. A. 419, 425. 

 Tail crested above at the end ; sides without a fulvous stripe j 

 hair very coarse and stiff, without any under-fur. 

 Hab. San Francisco, California, Colorado River. 



2. Perognathus fasciatus, Pr. Max. Nova Acta C. L. C. 

 Akad. xix. 1, 369, t. 24, 1859 ; Aud. & Bachm. N. A. Quad. iii. 341, 

 1854 ; Spencer Baird, M. N. A. 420. 



Tail simple ; ears large ; sides with a fulvous stripe. Above sandy- 

 coloured ; outside of fore legs and upper surface of the feet white ; hair 

 stiff and hard, like spun glass, without any under-fur. 



Hab. Kansas. 



