AKT. 4 BIRDS OF THE MENTAWI GROUP — EILEY 39 



long: as the type of zarhina. It has been named Arachnothera I. 

 niasensis van Oort.^^ 



There is quite a sexual difference in size, the females having consid- 

 erably shorter wings and bills, and it is probable that abnormally 

 small birds marked as males may be wrongly sexed. 



Seven males (including type of antelia) from Tenasserim and Trong, 



measure: Wing, 67.5-70 (68.6) ; eulmen, 37-41 (38.1). 

 Two males, (including type of melancluma) from east Sumatra measure: 



Wing, 70-71.5 (70.7) ; eulmen, 39-39.5 (39.2). < 



Five males from Siberut: Wing, 67.5-72.5 (68.9) ; eulmen, 37-41 (39.4). 

 Ten males from Sipora: Wing, 65-71.5 (68.6) ; eulmen, 35-40 (38.1). 

 Three males from North Pagi (including type of hypochra) : Wing, 



67.5-70 (68.5) ; eulmen, 38-40 (39). 

 Four males from South Pagi (including type of exochra) : Wing, 66-70 



(6S.5) : eulmen, 37.5-39.5 (38.4). 

 Three males from near Singapore (including type of heliocrita) : Wing, 



63-69 (66.8) ; eulmen, 33.5-35.5 (34.7). 

 Two males, Nias (one marked "female?", but from the measurements is 



a male) : Wing, 68.5-69 (68.7) ; eulmen, 4(K-42 (41). 

 Two males, Pulo Bangkaru, Banjak Islands (including type of zarhina) : 



Wi-g, 6S-71 (69.5) ; eulmen, 38.5-44.5 (41.5). 



A peculiar circumstance about the above averages (with one or two 

 exceptions) is their remarkable uniformity. 



ARACHNOTHERA CHRYSOGENYS ISOPEGA Oberholser 



Arachnothera chrysogenys isopega Oberholsee, Smiths. Misc. Coll., vol. 60, 



no. 7, 1912, p. 20 (Pagi Islands). 

 Arachnothera chrysogenys Chasen and Kloss, Ibis, 1926, p. 299. 



One male, Sipora. 



The above specimen is molting. It agrees fairly well with the tj^je 

 of isopega, which has a longer wing than any measured from the rest 

 of the range of the species represented in the United States National 

 Museum. The wing in the type of isopega measures 96 ; that of the 

 Sipora specimen, 87, but the latter would have possessed a longer 

 wing had the molt been completed. 'A female from South Pagi 

 Island also seems to have a longer wing than true chrysogenys. I 

 have only examined the three specimens from the Mentawi Islands. 



Three male specimens from Tapanuli Ba3% west Sumatra, the 

 original series of Arachnothera chrysogenys copha Oberholser, are 

 more yellowish above and below and have slightly shorter wings than 

 isopega. 



A male and female from Nias Island in the United States National 

 Museum represents the original material of Arachnothera chrysogenys 

 pleoxantha Oberholser.** The type (the female) is more yellowish 



^3 Notes Loyden Mus., vol. 32, no. 4, 1910, p. 195. 

 *' Smiths. Misc. C.^11., vol. 60, no. 7, 1912. p. 20. 



