THE BIRDS OF NORTHERN THAILAND 59 



With this migratory form I place three specimens from Chiang Mai : 

 An adult female and an immature of the same sex, respectively taken 

 October 19 and 20, 1935, and an adult male collected May 12, 1936. 



The two October examples are molting both remiges and rectrices. 

 The third specimen, shot at a surprisingly late date, had the gonads 

 quite inactive and doubtless represents a delayed north-bound migrant. 



The adult female had the irides red-orange; the cere and maxilla 

 black ; the mandible slaty black, plumbeous at the base ; the rictus pale 

 3 r ellow ; the feet and toes yellow ; the claws horny slate. The immature 

 differed only in having the irides olive-yellow. 



A general description of the plumages of this species will be found 

 under the following race. P. p. ruficollis is distinguishable from 

 gurneyi only by its greater size. 



Stresemann, in his revision of the genus Pernis (Archiv f ur Natur- 

 geschichte, 1910, pp. 137-193), states that ruficollis has the "tail-wing 

 index" (length of tail multiplied by 100 and divided by length of 

 Aving) usually under 65 mm.; the ""wing-tip" (distance from tip of 

 longest secondary to tip of longest primary) usually under 110 mm.; 

 the wing length from 392 to 460 mm. My adult male has the "index" 

 61 mm., the "wing-tip" 106 mm., the wing length 446 mm. ; the adult 

 and immature females respectively have the "index" 61 and 58 mm., 

 the "wing-tip" 78 and 97 mm., the wing length 423 and 444 mm. 

 Owing to the fact that both females are molting the quills of wings and 

 tail, their measurements are misleadingly short, yet great enough to 

 place them under this name without question. 



PERNIS PTILORHYNCUS GURNEYI Stresemann 



Burmese Honey Buzzard 



Pernis ptilarhynchus gurneyi Stresemann, Arch, fiir Naturg., new ser. Abt. B, 

 vol. 9, No. 2, 1940, pp. 168-170 (Lamaing, near Mandalay, Burma). 



Pernis apivorus ruficollis [partim], Deignan, Journ. Siam Soc. Nat. Hist. Suppl., 

 1936, p. 75 (Chiang Mai). 



Pernis apivorus orientalis [partim], Deignan, Journ. Siam Soc. Nat. Hist. Suppl., 

 1936, p. 75 (Chiang Mai). 



At Chiang Mai I obtained specimens of this small subspecies Octo- 

 ber 1 and December 13, 1935 ; February 25, 1936 ; January 20, Febru- 

 ary 4 and 6, 1937. Others reached me from Ban San Kamphaeng, 

 January 4, 1936, and Doi Suthep (3,500 feet), December 16, 1935. 

 With P. p. gurneyi may be placed also an undated adult male in 

 Stockholm, taken by Eisenhofer at Khun Tan; this is the bird dis- 

 cussed by Lonnberg (Ibis, 1924, p. 321). Finally, I have seen in 

 Hannover an unsexed example, collected by Eisenhofer in "Siam," 

 March 9, 1911, which probably is of this race and may well have come 

 from some northern locality. 



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