296 BULLETIN 15 3, UNITED STATES NATIONAL MUSEUM 



it is replaced by chadensis. This form is so distinct as to be almost 

 a species. The underparts are creamy white, with or without a 

 slight grayish-buff tinge; the superciliaries are very broad and are 

 pure white anteriorly, pale tawny posteriorly; the hind neck and 

 upper back sandy tawny; the inner as well as the outer webs of the 

 remiges wholly rufous basally, whereas in the other races the inner 

 webs are fuscous basally with a narrow rufous margin; wings, 

 87-97 mm. 



6. P. s. sudanensis: The Lado Enclave, Mongalla, Upper Nile, 

 Balir el Ghazal, and Sennar districts of the Sudan, to central Ethi- 

 opia (east to the region between Lakes Tsana and Zwai; in other 

 words, the Ethiopian regions drained by the tributaries of the Nile 

 system). This form is characterized by its dark back, which is 

 distinctly grayish brown with no rufous; the underparts are clear 

 gray ; wings, 77-88 mm. Sclater has recently claimed that this name 

 is a synonym of erlangen, but I find sudariensis to be constant in its 

 characters. 



7. P. s. hdbyssinicus: Eritrea, northern Ethiopia, and most of 

 British and French Somaliland, intergrading with sudanensis near 

 Lake Tsana and with erlangeri in the Hawasli Valley near Harrar 

 and Dire Daoua. This form is dark-backed, but has the back more 

 rufous, less grayish than in sudanensis,' underparts gray as in suda- 

 nensis; size smaller; wings, 73-85 mm. 



8. P. s. percivali: Southwestern Arabia. Similar to hahyssinicus 

 but darlvcr below, and somewhat smaller; wings, 78-80 mm. (None 

 seen by me.) 



9. P. s. erlangeri: Southern Ethiopia (the Shoan Lakes region, 

 Gallaland, and the Omo district) south to the neighborhood of Lake 

 Kudolf, Similar to hahyssinicus but slightly larger; wings, 81.5- 

 89.5 mm ; the nape slightly lighter than the back. 



Sclater " states that erlangeri^ hahyssinicus^ and percivali differ 

 from the other forms in having no dusky cross bands on the central 

 tail feathers. This character does not hold at all well. I find that 

 erlangeri^ for example, has these markings just as well developed as 

 does erythrojjferus. 



The size variations of the present series are shown in table 57. 

 Although erlangeri is, on the whole, slightly larger than hahyssinicus^ 

 the northern specimens (from the Hawash Basin) are not smaller 

 than others from southern Shoa but, on the contrary, have longer tails. 



In color the variations affect all parts of the bird. The super- 

 ciliaries vary from wholly white to white anteriorly and yellowish 

 buff posteriorly; the middle rectrices from earth brown barred with 

 dusky fuscous to almost pure fuscous. The latter character varies 



y In Shelley, The birds of Africa, vol. 5, p. 361, 1912. 



