1878.] MR. D. G. ELLIOT ON THE PTEROCLIDAE. 237 



these interesting specimens. There is a slight difference observable 

 in their size, one being rather stouter than the other; and they evidently 

 belong to two individuals, perhaps different sexes of the same species ; 

 and, as stated by Monsieur A. Milne-Edwards 1 , represent a species 

 between the P. alchata, Linn., and the P. gutturalis, Smith. 



The following are the genera proposed for these birds, with the 

 type of each added : — 



Type. 



(1811) Syrrhaptes, Illiger, Prodr. p. 243 Tetrao paradoxus, Pall. 



(1812) Nematura, Piscb. Mem. Soc. Natur. Moscou Tetrao paradoxus, Pall. 



(1815) Pterocles, Temm. Man. Ornith. p. 299 Tetrao alchata, Linn. 



(1816) QSnas, Vieillot, Analyse, p. 52 Tetrao alchata, Linn. 



(1816) Heteraclitus, Vieillot, Analyse, p. 53 Tetrao paradoxus, Pall. 



(1856) Pteroclurus,Bon. Compt, Rend.xlii. p. 880 Tetrao alchata, Linn. 



Geographical Distribution. 



The Pteroclidae have been found in only three of the zoogeogra- 

 phical divisions of the earth's surface, viz. the Palsearctic, Oriental, 

 and Ethiopian regions ; and in these they are chiefly restricted to 

 tracts devoid of cultivation, or actual deserts. From the fact that 

 of the sixteen known species twelve are met with in the Ethiopian 

 region, we may safely regard the Pteroclidae as having originated in 

 Africa, from which they spread into the other two regions named 

 above. Of the twelve Ethiopian species, seven (or a little over half) 

 are not found in the other zoogeographical divisions. In the 

 Oriental region, which is the next richest in the birds of this family, 

 seven species are found, one of which is peculiar to it ; and, lastly, 

 the Paleearctic region is tenanted by five species, two of which, 

 constituting the genus Syrrhaptes, are not found elsewhere. Com- 

 mencing with the Ethiopian region, where the species appear confined 

 mainly to the eastern side of the continent, we find the Pt. gut- 

 turalis extending its range from Abyssinia to Kurrichane, just north 

 of the Cape Colony, where it was procured by Sir A. Smith. In 

 Egypt and Nubia Pt. eoronatus is found, not going south of the 

 last-named country on this coast. It is also met with in the 

 southern part of the desert of Sahara, and again on the plains of the 

 Sinaitic peninsula, and probably occurs throughout Arabia, as, together 

 with the three species next mentioned, it is found in Sindh of the 

 Oriental region. In the region extending from and including 

 Egypt to the Somali country Pt. exustus, Pt. senegalus, and Pt. 

 lichtensteini are found ; while Pt. quadricinctus appears to be re- 

 stricted to Abyssinia and Sennaar, although given by Swainson as 

 a bird of West Africa under the name of Pt. tricinctus. Passing 

 southwards along the same coast, we find Pt. variegatus, Pt. 

 namaqua, and Pt. bicinctus inhabiting the Trans-Vaal, whence 

 they range across this part of the continent into Damaraland. 

 Somewhere in the interior of Eastern Africa Pt. decoratus dwells, 

 according to Cabanis ; but its precise distribution does not appear 



1 Oiseaux Fossiles, torn. ii. p. 295, pi. 141. figs. 1-9. 



