20 BULLETIN 186, UNITED STATES NATIONAL MUSEUM 



3. The appearance in September, presumably from the more south- 

 ern parts of Thailand, of immature green herons and night herons; 

 these birds are present only for a short period before again 

 disappearing. 



4. The descent of individuals of numerous species in greater or 

 smaller numbers from the mountains to the adjacent plains during 

 the cold weather. 



5. The extensive wanderings of parrots, hornbills, bulbuls, and 

 other frugivores in accordance with the ripening of fruits and the 

 flowering of ornithophilous trees. 



FAUNISTICS 



Following Boden Kloss's zoogeographical divisions for Thailand 

 (Journ. Nat. Hist. Soc. Siam, vol. 1, 1915, pp. 250-251, map), it has 

 been generally accepted that all Thai territory north of an east- west 

 line at latitude 17°47' N. belonged to a single faunal area, named by 

 Kloss "Northern Siam." Kloss's decision was based almost entirely 

 upon the material brought together by Gyldenstolpe during his first 

 visit to the North ; a glance at his itinerary will show that the entire 

 collection was made in the lower parts of Phrae Province and was 

 naturally wholly homogeneous. 



My own researches have shown clearly that within Kloss's "North- 

 ern Siam" we are concerned with no less than three distinct, although 

 related, faunas. The first of these is restricted to the territory watered 

 by the Mae Khong and its tributaries (Chiang Rai Province) ; the 

 second, to the systems of the Sal win and the Mae Ping (Mae Hong 

 Son and Chiang Mai Provinces) ; the third, to the provinces drained 

 by the Mae Wang, the Mae Yom, and the Mae Nan (Lampang, Phrae, 

 and Nan). (Map 3.) 



NORTH 



The province of Chiang Rai, most northern of all Thailand, lies 

 completely in the basin of the Mae Khong and is nothing more nor 

 less than a purselike extension of the river valley, clearly and com- 

 pletely demarcated from its more southern sister-provinces by forest- 

 clad ranges that probably at no point are lower than 3,000 to 3,500 

 feet. 



The greater part of the province consists of great marshes and 

 savannas, the characteristic inhabitants of which are birds, chiefly 

 aquatic forms, that have reached their present home by way of the 

 river from districts farther south and east and which, since the stream 

 here leaves Thai territory temporarily, appear again in Thailand 

 only much farther south. Among them may be mentioned Pelecanus 



