346 BULLETIN 15 3, UNITED STATES NATIONAL MUSEUM 



birds decrease in size from the southern to the northern part of 

 the range, and have been divided on this basis into three currently 

 recognized forms. The typical race, with a wing length of from 

 105-110 millimeters, is found only in South Africa, intergrading 

 with the next in Southern Rhodesia and southern Mozambique, 

 The tropical East African form, orie?italis, with wings 96-105 milli- 

 meters long, occurs from the northern limits of the typical race, 

 through Rhodesia, the Katanga, Lower Congo, Angola, Nyasaland, 

 Mozambique, Tanganyika Territory, and Kenya Colony to as far 

 north as Kanyakeni (south of Meru). The northernmost of the 

 three races, eriangreri, is definitely loiown only from southern 

 Somaliland. It has a wing length of from 92-97 millimeters. 

 Granvik ^* records three birds from Mombasa as erlangeri, but gives 

 the wing lengths as 98 millimeters for the male and 95-96 millimeters 

 for the two females. The first is obviously within the variational 

 limits of 07'ientalis^ and the others are close to it. Furthermore, he 

 admits that all three birds were in molt when shot. While it is 

 not stated whether the remiges (and consequently the wing measure- 

 ments) were affected by the molt, this uncertainty, together with the 

 fact that van Someren ^^ and others record orientalis from Mombasa, 

 suggests that Granvik's birds are also orientalis. 



I have examined a series of 17 orientalis and 10 alhiventi^is and 

 find the size distinctions to hold fairly well. Likew^ise, the latter 

 differs from the former in having the pectoral area more streaked 

 with black. The size limits of orientalis and albiventris overlap 

 more than has hitherto been thought. The present immature male 

 from the Tana River is the largest example of orientalis examined 

 and exceeds in size any recorded measurements. It has a wing length 

 of 107 millimeters, tail 69 millimeters, culmen 46 millimeters. The 

 female is considerably smaller — wing 101 millimeters, tail 64 milli- 

 meters, culmen 43 millimeters. The overlapping in size of e/rlaiigeH 

 and orientalis is also greater than has been supposed. A male adult 

 from Dar es Salaam, in the Museum of Comparative Zoology, has 

 a wing length of onl}'^ 93 millimeters, but a female taken at the 

 same time has a wing 98 millimeters long. The eastern form orien- 

 talis is really nothing but an intermediate race bridging the gap be- 

 tween albivcntris and erlangeri. As intermediate forms go, it is 

 quite distinct. 



Immature birds have the feathers of the throat and breast termi- 

 nally edged with earth brown, giving the pectoral region a somewhat 

 scalloped appearance. This is better developed in alMventris than in 

 orientalis., and in the former this scalloping is continued down the 

 sides and upper thinks. 



'*Jouin. f. Ornith., 1923, Sonderheft, p. 104. 

 ■"Nov. Zool., vol. 29, 1922, p. 76. 



