KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 57. NIO 2- 



Presbytis obscura halonifer. Cant. 



£ Koh Lak Paa, near the boundary to Tenasserim *j\t 1914. — $ Koh Lak Paa 7 /iä 1914. — 

 ö Koh Lak Paa, january 1915 (skull only) — 1 juv. Koh Lak Paa, january 1915 (skull only). 



The northern mainland form of the Dusky Langur has been separated by Cantor 

 under the name of P. halonifer. 



It was fairly common in the forests on the boundary between Siarn and Tenasserim 

 where several specimens were shot. It generally goes about in small parties affecting 

 the higher trees in dense jungles. Like the other Langurs it is rather shy and by no 

 means easy to obtain. It has a hoarse rather uncanny note which is frequently heard. 

 When being disturbed in some way by the presence of man it has the habit of conceal- 

 ing itself among the foliage of the trees from which it then suddenly jumps, making a 

 shot very difficult. 



Along the coast of the Gulf of Siarn several isolated limestone hills are to be found. 

 Some of these hills are very precipitous and covered with a dense vegetation of^ever- 

 green trees. These hills seemed to be inhabited by another member of the obscura Group 

 (vide infra). 



Skull measurements ö" 



& 



6 



Greatest length | 101,0 mm. 



99,5 mm. 



93,9 mm. 



Basicranial length . . . 









72,3 » 



70,0 » 



65,7 » 



Condylobasal length . . . 









79,0 » 



76,0 » 



71,2 » 



Occipitonasal length . . . 









78,3 » 



78,3 » 



78,5 » 



Zygomatic width .... 









73,0 » 



77,0 » 



69,0 » 



Width of brain case . . 









61,0 • 



60,0 » 



57,2 » 



Least postorbital breadth 









41,2 » 



45,0 » 



42,0 » 



Least interorbital breadth 









8,5 » 



9,0 » 



8,0 » 



Length of palate mesially 









35,0 » 



31,0 » 



31,0 » 



Length of upper molar series 





24,6 » 



26,0 » 



23,2 » 



Length of lower molar series 





32,0 » 



32,0 » 



29,0 » 



Length of upper toothrow from frön t 







of canine to back of last 



ii 



101 



ar 



31,2 » 



32,3 » 



29,2 » 



Presbytis obscura flavicauda. Elliot. 



Proc. U. S. Nat. Mus. vol. 38 1910 p. 352. 



$ Koh Lak, Siamese Malaya i h-> 1914. — Nose to vent = 435 mm.; tail = 610 ram. — $ Koh 

 Lak S9 /ii 1914. — Nose to vent = 495 mm.; tail = 710 mm. 



This species inhabits Peninsular Siarn and southern Tenasserim. 



During my stay at Koh Lak I obtained two specimens which I, though with some 

 hesitation, ha ve referred to the above-mentioned species, the type of which came from 

 Träng. 



