230 Mr. D. A. Bannerman on an Ornithological 



these islands, a similar environment to that of their native 

 land, they have settled down and remained quite unchanged 

 from the typical race. 



Then take the case of the Pale Titmouse {Parus caeruleus 

 degener) ; this has become greatly modified on account o£ 

 the unusual surroundings amongst which it now lives and, 

 as in the case of many species inhabiting the waterless desert 

 islands of Fuerteventura and Lanzarote, it is both smaller 

 in size and paler in colour than allied forms living on the 

 well-watered and mountainous western islands. 



A particularly interesting case is that of the Barn 

 Owls, of which there are two forms in the Archipelago. 

 The subspecies already mentioned, Tyto flammea gracili- 

 7'ostris, is confined to the eastern desert group, where it 

 lives in the holes of cliffs and ekes out a precarious 

 existence, l^urning to the western group of islands, we 

 find that they are inhabited by a Barn Owl living under 

 normal conditions which cannot be separated from dark 

 examples of typical Tyto flammea flammea. 



Provided that sufficient characters meriting subspecific 

 rank are shown to be constant, I have accepted the names 

 proposed, but undoubtedly several new forms have been 

 recently described which can never be regarded as worthy 

 of separation. Size alone is often a very dangerous char- 

 acter upon which to make a new subspecies ; but the 

 physical characteristics of the Canary Archipelago, especially 

 as regards the eastern islands, tend to produce geographical 

 races which have become modified in colour as well as in 

 size. In the group with which this paper deals, Fuerte- 

 ventura, Lanzarote, Graciosa, and the four outlying islets, a 

 very distinct avifauna is to be found. This fauna, as might 

 be expected, is allied to that of northern Africa, while that 

 of the western islands is almost entirely European in 

 character. 



In the first part of my paper I have attempted to describe 

 the physical peculiarities of the country through which I 

 passed on my journey. Anyone who is acquainted with the 

 western islands will not, therefore, be surprised at the number 

 of forms peculiar to the eastern group alone. 



