116 CONTROLLED NATURAL SELECTION 
pression of the utility of the theory is thereby 
obtained, because it appears necessary to so 
frequently strain it. Theories are usually 
substantiated by chosen facts. It is well, 
therefore, to state that 173 birds have been 
considered, and only a few have required to 
be reviewed. 
Taste I.— BIRDS OF PREY 
fr Marsh Harrier. . Circus eruginosus 
Hen Harrier . . C. cyaneus 
Montague’s Harrier C. cineraceus 
Buzzard . . . . Buteo vulgaris 
Golden Eagle . . Aquila chrysartus 
Falconide + White-tailed Eagle aliartus albicilla 
*Sparrow Hawk. . Accipiter nisus 
Osprey . . . . Pandion palietus 
Peregrine Falcon . Falco peregrinus 
Merlin. . . . F. esalon 
\ Kestrel . . . . Tinnunculus alaudarius 
oT een ee Richardson’s Skua 8. crepidatus 
Common Skua . S. catarrhactes 
Heron . . . . Ardea cinerea 
{* Mimicked by cuckoo, Cuculus canorus. ] 
Taste II.—NIGHT BIRDS 
Barn Owl . . . Strix flammea 
Long-eared Owl . Asio otus 
Strigide { Short-eared Owl . A. brachyotus 
Tawny Owl. . . Syrnium aluco 
Little Owl . . . Athene noctua 
