NO. 2188. MAMMALS FROM ISLANDS OFF SUMATRA— LYON. 447 



Diagnostic characters. — Distinguislied from the typical subspecies 

 and the next by having a short, wide, heavy rostrum, temporal 

 ridges better developed and more angular, upper parts in many 

 specimens, with a tendency to be dark and blackish. 



CbZor.— Essentially like that of Rattus simalurensis sirrwlurensis 

 (Miller) (1903a) aside from the tendency already mentioned to dark- 

 ness on upper parts. 



SlcuU and teeth.— The skull is distinguished by its heaviness and 

 angularity, especially seen in the wide heavy rostrum, aaid the heavy 

 angular temporal ridges. While these characters are those usually 

 produced by age, yet they are not found in examples of Rattus 

 simalurensis siTualurensis of equal age. Young examples show a 

 wider rostrum than is found in yomig examples of the Simalur and 

 Siumat rat. 



Measurements. — Type: Head and body, 231 mm.; tail, 225; hind 

 foot, 42; condylobasal length, 47.8; zygomatic width, 24.4; brain 

 case, 17.7; maxillary tooth row, 7.9. 



Specimens examined. — Thirteen from Pulo Lasia. 



RATTUS SIMALURENSIS BABI, new subspecies. 



Type-specimen. — No. 114280, U.S.N.M., skull, without skin, of 

 adult male, collected on Pulo Babi, January 13, 1902, by Dr. W, L. 

 Abbott. 



Geographic distribution. — Pulo Babi. 



Diagnostic characters. — Similar to the rat of Pulo Lasia, but with a 

 heavy elongated skull. 



Color. — Skins of the two specimens collected were not saved, the 

 labels accompanying the skulls read: ''Large gray rat similar to that 

 of Pulo Lasia" for Cat. No. 114280, and for the other specimen Cat. 

 No. 114281, collected a day later, "Large brown rat similar to that 

 of Pulo Lasia." 



Slcull.— The skull is heavy but lacks the breadth and angularity 

 of that of Rattus simxilurensis lasiae, rostrum is moderately long and 

 slender, temporal ridges are not angular, but are well defined and are 

 inclined to appear somewhat parallel. 



Measurements. — Type: Head and body, 255 mm.; condylobasal 

 length, 50.2; zygomatic width, 23; width of brain case, 17.4; maxillary 

 tooth row, 8.3. The tail of the type-specimen was imperfect; what 

 there was of it measured 205 mm., tail of the other specimen, 217. 



Specimens examined. — Two skulls without skins. 



RATTUS BALMASUS. new species. 



Type-spedmen. — No. 121765, U.S.N.M., skm and skull of adult 

 female, collected on Tana Bala, Batu Islands, February 13, 1903, by 

 Dr. W. L. Abbott; original number 2286. 



