Expedition to the Eastei-n Canary Islands. 231 



In many cases, distinct, but closely allied geographical 

 races are found to occur, the one in the eastern, the other 

 in the western group. 



Of these we may mention the following, arranged in 

 tabular form : — 



Subspecies peculiar to the 

 Eastern Canary Islands. 



Acanthis cannabina harterti. 



Calandrella minor j)olatzeki. 

 (Also found in Gran Caiiaria, 

 although this latter form has 

 been separated on what I 

 consider to be insufficient 

 grounds.) 



Parus cceruleus deyener. 



4. Phylloscoptis collybita exsul. 



5. Tytojlammea gracilirostris. 



6. Tinnunculus 



dacoticB. 



7. (Edicnemus 



sularuyn. 



tinnunctdus 



cedicnemus in- 



Closely allied form inhabiting 

 the Western Canary Islands. 



1. Acanthis cannabina nana. 



2. Calandrella minor rufescena. 



3. Pariis ccerideus teneriffcB. Tene- 



rife ; Gran Canaria ; Gomera. 

 Parus c<eruleus ombriosus. 



Hierro. 

 Parus ccsruleus palmcs. Palma. 



4. Phylloscoptis collybita canari' 



ensis. 



5. Tyto Jlammea Jlammea. 



6. Tinnunculus tinnunculus canari- 



ensis. 



7. (Edicnemus cedicnemus dis- 



iinvtus. 



On comparing the eastern with the western subspecies, 

 it will be seen that those from the eastern group are, with one 

 exception — Tyto flammea gracilirostris, — lighter in colour 

 than the birds from the western islands. This is easily 

 comprehended when we realise that the eastern islands are, 

 as Canon Tristram correctly expressed it, "biologically 

 simply western outliers of the Great Sahara,'^ without any 

 of the rich vegetation wliich clothes the mountainous 

 western islands. The birds, therefore, which inhabit the 

 eastern group have with the action of time learnt to harmo- 

 nise more exactly with the desert surroundings amongst 

 which they are placed. 



Several Families are confined almost if not entirely to 

 the eastern group, and are not represented by any species in 



