NILS GYLDENSTOLPE, THE SWEDISH ZOOLOGICAL EXPEDITIONS TO SIAM. 



The Langurs belonging to the obscura Group are very variable both as to size and 

 colour, and without a large material to compare with the different forms are almost im- 

 possible to be properly recognized. In life the skin round the eyes and the lips are pure 

 white. 



Skull measurements 



Greatest length 



Basicranial length 



Condylobasal length 



Occipitonasal length 



Zygomatic width 



Width of brain case 



Least postorbital breadth 



Least interorbital breadth 



Length of palate mesially 



Length of upper molar series . . . 



Length of lower molar series . . . 



Length of upper toothrovv from front 



of canine to back of last molar . 



90,0 mm. 



81,0 mm 



64,0 » 



54,0 » 



71,2 >» 



62,0 » 



76,8 » 



73,2 » 



65,0 » 



59,3 » 



57,0 » 



55,0 » 



43,0 » 



42,2 » 



8,3 » 



6,0 » 



28,0 » 



25,5 » 



24,0 » 



22,0 » 



29,6 » 



25,5 » 



29,5 » 



26,1 » 



Presbytis crepuscula. Elliot. 



Ann. & Mag. Nat. Hist. ser. 8. vol. IV. 1909 p. 270. 

 J* Koon Tan, Northern Siarn 2 /e 1914. — Nose to vent = 395 mm.; tail = 530 mm.; ear = 35 mm. 



This species seems to be somewhat rare in collections and in the British Museum 

 there are only two specimens, both of which were obtained at the Mooleyit mountain 

 in Tenasserim. During my former Expedition to Siarn I obtained a single male specimen 

 which was shot near the Meh Lem river in Northeastern Siarn. During my last journey 

 another male specimen was obtained some distance due west from the Meh Lem and 

 at about the same latitude. 



This specimen, though younger, is of exactly the same colour throughout. The skin 

 round the eyes is bluish grey in life and the lips are white. 



Skull ?neasurements: 



Greatest length = 85,o; basicranial length = 53, o; condylobasal length = 60,5 ; 

 occipitonasal length = 75,o; zygomatic width = 57,5 ; width of brain case = 54,s; 

 least postorbital breadth = 43,o; least interorbital breadth = 5,s; length of palate 

 mesially = 23,7; length of nasals mesially = 11,3 mm. 



Macaca irus. Cuv. 



The Crab-eating Monkey was observed along the lower course of the Menam Chao 

 Phaya River and in a mangrove swamp a few miles north of Koh Lak in the Siamese 



