127 [Vol. xliii, 



to the areas inhabited by one or other o£ the respective 

 local races can at present only be explained as due to 

 Environment, and that the climatic conditions within the 

 area are so locally and abruptly altered that the species 

 within that area is still unstable and not fixed. Finally, 

 we have a few cases of " Hybrids," which originated spora- 

 dically, but, owing to the offspring, unlike the majority of 

 hybrids between well-defined species, being, fertile, have in- 

 creased in number, as to give the mistaken idea of " Racial 

 Hybrids," such are the many hybrids in Algeria between 

 Passer domesticus tingitanus and Passer hispaniolensis his- 

 paniolensis. 



The only definite conclusion one can come to, in view of 

 these varied examples of the two groups of " Hybrid ^' forms, 

 is that, in the first place, "Hybrids'''' of the last-mentioned 

 category do occasionally find a place as a factor in the evolu- 

 tion of new species. In the case of what I have termed 

 " Racial Hybrids," they will, in all probability, eventually 

 in such cases as the Paradiscea become a fixed local race ; 

 but in the oases such as the Rock-Thrushes and Kaleege 

 Pheasants an intermediate form may become fixed, all 

 other variations, together with the two extreme local races, 

 dying out. 



The following is a list of the specimens exhibited, together 

 with the parent species and local races respectively : — 



Racial Hybrids. 



(1) Corvus corone L, X Corvus corone comix L. 

 1 c? ad., C. c. corone. Ingelheim, April 1910. 

 1 ? ad., C. c. comix. Tring, Dec. 1893. 



Racial Hybrids : — Three S c?, Rentendorf (Brehm coll.), 

 July 1818, Feb. 1820, March 1845 \ I S , Ingelheim, Dec. 

 1905 ; 1 ?, Jardine Hall (Sir W. Jardine coll.) ; 1 Torre de 

 Lago, Italy, Oct. 1906 ; 1 Gertenbach, Germany, Sept. 1890 

 (E. Hartert coll.). 



(2) Turdus naumanni naumanni Temm. X Turdus naumanni 

 eunomus Temm. 



