14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 6l 



worn), 38.6; zygomatic breadth, 19.9; interorbital constriction, 6.2; 

 occipital breadth, 15.6; depth of braincase, 10.4; nasal, 15.3; dias- 

 tema, 11.0; mandible, 24.5; maxillary toothrow (alveoli), 7.2; man- 

 dibular toothrow (alveoli), 6.7. 



Specimens examined. — Six, all from Pulo Lankawi. 



EPIMYS RATTUS DENTATUS, new subspecies 



Type. — Adult male (skin and skull), No. n 1929, United States 

 National Museum. Collected on Hastings Island, Mergui Archi- 

 pelago, December 13, 1900, by Dr. W. L. Abbott. Original No. 783. 



Diagnosis. — Like the form of Epimys rattus occurring in Trong 

 and southern Tenasserim but cheek teeth decidedly larger, exceeding 

 those of E. rattus viclana. 



Measurements. — Type: head and body, 180 mm.; tail, 190; hind 

 foot (dry), 36 (34) ; condylobasal length of skull (teeth much 

 worn), 39.0; zygomatic breadth, 19.8; interorbital constriction, 6.0; 

 occipital breadth, 15.8; depth of braincase, 11.2; nasal, 15.2; dias- 

 tema, 1 1.7; mandible, 24.1 ; maxillary toothrow (alveoli), 7.0; man- 

 dibular toothrow (alveoli), 7.0; mandibular toothrow (alveoli), 6.6. 



Specimens examined. — Eight (one odd skull), all from Hastings 

 Island. 



Remarks. — The large size of the cheek teeth in this form, as in all 

 those now known from the Mergui Archipelago, is immediately 

 evident on comparison with specimens from the adjoining mainland. 

 In the insular races the width of m 1 usually equals arid often exceeds 

 half the least palatal width, while in the mainland animals it is us- 

 ually less than half. 



EPIMYS RATTUS INSULANUS, new subspecies 



Type. — Adult male (skin and skull), No. 104147, United States 

 National Museum. Collected on Heifer Island, Mergui Archipelago, 

 March 7, 1900, by Dr. W. L. Abbott. Original No. 334. 



Diagnosis. — Like Epimys rattus dentatus but general outline of 

 skull narrowed. 



Measurements. — Type: head and body, 185 mm.; tail, 185; hind 

 foot (dry), 36.5 (35.5) ; condylobasal length of skull (teeth moder- 

 ately worn), 40.6; zygomatic breadth, 18.6; interorbital constriction, 

 6.3; occipital breadth, 16. 1 ; depth of braincase, 11.2; nasal, 15.4; 

 diastema, 11.3; mandible, 24.1; maxillary toothrow (alveoli), 7.6; 

 mandibular toothrow (alveoli), 6.9. 



Specimens examined. — Six, all from Heifer Island. 



