352 PROCEEDINGS OF THE VATIONAL MUSEUM. vol. 38. 



tracted, widening al posterior e< I ^> of palate: basi-occipital wider, the 

 lateral pits much smaller; zygomatic arch longer and more curved; 

 occipital region broader; brain ease longer and wider and orbits 

 higher than wide, not round; mandible and lower tooth row longer. 



Color. Very like P. o. carbo, except the nuchal crest is creamy 

 white and the tail is pale bully gray. 



Measurements. Total length, 703.20 mm.; tail. .">ns; skull, total 

 length, 98.8; occipito-nasal length, si. 7: hensel, 70.5; zygomatic 

 width. T.'i.v intertemporal width. 40.6; palatal length, 31.2; length 

 of upper molar series, 27.3; length of mandible. (17.1 ; length of lower 

 molar series, •"> I..'!. 



The island allies of /'. obscura are apparently characterized by hav- 

 ing much larger teeth than are seen in typical individuals and by the 

 main cranial distinctions mentioned above. 



PYGATHRIX FLAVICAUDA, new species. 



Type-locality. Trong, Lower Siam. 

 / ,pe. Cat. No. 83259, I'.S.X.M. 



<,i n< ml characteristics. -Belonging to P. obscura group, but legs 

 from hips pale smoke gray and tail cream color. 



Geographical distribution. Lower Siam and southern Tenasserim; 

 ECisseraing and Sir William dames islands, Mergui Archipelago. 



Color. Face bare, upper lip and space over eve flesh color, darker 

 aboul nose and beneath eyes. Hairs on forehead long upright and 

 extending to ears brownish black; hairs on lips and lower cheeks 

 long and extending backward beyond ears blackish; top of head and 

 nape yellowish white: dorsal line mummy brown, paler than back; 

 rest of upper parts and flanks black tinged with brown; outer side 

 of arms very dark hair brown with a reddish tinge on shoulders 

 and grading into black on wrists and hands; throat sparsely covered 

 with dark brown hairs; under parts grayish brown; outer side of legs 

 smoke gray with a brownish tinge from knee to ankle; feet blackish; 

 tail uniform cream color. 



Measurements. Total length, 1,257 mm.: tail. 724: skull, total 

 length, 94.7; occipito-nasal length, 77; hensel. 66.5; zygomatic 

 width. 70; intertemporal width, in. 7: palatal length, 32.7; median 

 length of nasals, «.>•'!: length of upper molar series. 24.4: length of 

 mandible. 68.6; length of lower molar series, 30. 



This very distinct species ran at once be recognized by its cream 

 color tad and pale legs. The examples from the islands, consist- 

 ing of only a male and female, differ slightly in certain particulars. 



The legs are e\ ( -n paler than those of the type, hands and feed jet 

 black, >t rongly conl rasted with t he arms and legs, and the skulls have 

 a flatter brain case and broader rostrum. The material is hardly 

 sufficient \<> enable a definite decision to be reached, and 1 leave these 

 island examples under the name of the present species. 



