68 BUZZARD—CA:CA 
breed, yearly in the New Forest, does not come into the sub- 
family Buteoninx, but is probably the type of a distinct group, 
Pernine,! of which there are other examples in Africa and 
Asia. The so-called “Turkey-Buzzard” is one of the American 
VULTURES. 
C 
CAICA, a pair of blindsacs or lateral dilatations of the gut, 
marking the beginning of the rectum. When the ceca are large the 
rectum is shut off from the ileum or small intestine by a valvular 
sphincter, which allows the feecal matter to ascend from the rectum 
into the ceca, but prevents it from passing back into the ileum. 
The czca vary extremely in size in the different groups of Birds ; 
they attain their greatest size in those that are herbivorous, are 
small or hardly functional in most that live on animal food, and are 
altogether absent in fruit- and grain-eaters. There are, however, so 
many exceptions to this broad generalisation, that an enumeration 
is advisable, especially since a certain taxonomic value cannot be 
denied to these organs. 
It is highly probable that originally all Birds possessed ceeca, 
and that, according to the diet, these were either further developed 
or reduced in size or even lost ultimately. Hence the mere 
presence of ceca in a bird is of less taxonomic value than their 
state of development; they are either functional, or without func- 
tion ; their absence is only the last step of their degeneration. 
1. The ceca are large and of great functional importance in 
Struthio, Rhea, Apteryx, Crypturi, Galline, Pteroclide, Gralle, and 
Anseres, 7.¢. in birds which are chiefly herbivorous ; also in many 
worm-eating Limicole, for instance in the Avoset, Lapwing, Ringed 
Plover, didicnemus, Thinocorys, Attagis, and the Corncrake ; lastly in 
the Owls, Nightjars, Rollers, Bee-eaters, and Cuckoos, i.¢. birds which, 
with the exception of the first group, are strictly insectivorous. 
2. The ceca are distinctly functional, but comparatively short, 
in Casuarius, Dromeus, Grus, Turnix, many Anatide (vegetable- 
eaters with a great predilection for animal food), Limicole and 
Rallide, like the Golden Plover, Numenius, Totanus, Gallinago, 
Chionis, Porphyrio, Porzana; the piscivorous Spheniscide, Pelli- 
canus, Podicipes, Uria, Colymbus ; Merops, and Phcenicopterus. 
3. The cxca are quite degenerated and functionless, being 
either (a) reduced to small wartlike or vermiform appendages, as 
in some Spheniscidx, Herodii, Pelargi, Steganopodes, Laride, Strep- 
1 The name Pernis was given in 1817 by Cuvier (Régne Anim. i. p. 822), who 
said it was used by Aristotle ; but the latter has only mrrépyis (Hist. Anim. ix. 36). 
