SUMMARY OF THE INDIAN MAMMAL SURVEY, 



791 



close to it. Thomas also has described (A. M. N. H. (7), xx., p. 

 206, 1907) a species, rogersi, from the Andaman Islands. All these 

 forms may be arranged in a key as follows :-^ • 



Key to the species of Rattus. 



A. — Tail nnicolor throughout, above and 

 below. 

 a. Hind-foot 45 mm. or more. 



a^ Size very large, hind-foot 56mm. 1. validus, Mill. 



■ 2. andafnanensis, Bl. 



. 3. rattus group. 



(for key see below) . 

 4. concolor, Bl. 



6^ Size smaller, hind-foot 45 mm. 

 b. Hind- foot less than 40 mm. 

 a'. Mammae, 10 or 12 



6'. Mammae 8 

 B. — Tail not unicolor. 



a. Tail bicolor, distal portion white. 

 a\ Mammae 3 -2 = 10. 



a^. Size smaller, hind-foot 37 mm... 5. manipulus, Thos. 

 6\ Size larger, hind- foot 48 mm. or 

 more. 



a 



Hind-foot about 48 mm. : at 



a 



7. m. fece, Thos. 



8. howersi, And. 



10. blanfordi, Thos. 



11. rogersi, Thos. 



least one-third of tail white 6. macJcenziei, Thos. 

 b^. Hind-foot about 5 1 mm.; only 

 extreme tip of tail white... 

 Mammae less than 10. 



Two rairs of pectoral mammee. 

 a^ Smaller, hind-foot about 37 



mm. 

 b\ Larger, hind-foot about 47mm. 9. lister i, Thos. 

 b'. Only one pair of pectoral 

 mamnife. 

 a". Mamm« 1 — 2 ==6 ... 



h\ Mamma? 1 — 3 = 8 



Tail throughout dark above, pale 



below. 

 a\ Mammas 3—2=10. 



a'. Upper incisors thrown forward, 

 forming an obtuse angle with 

 the palate, 

 a". Upper molar series 6*5 mm. 



in length ... 

 b^. Upper molar series 6 mm. in 

 length 

 6\ Upper incisors not thrown for- 

 ward, forming a right angle 

 with the palate ... 



12. berdmorei, Bl. 

 13.6. midlulus, Thos. 



14. vicerex, Bonh. 



