ALTMIOXTARV TRAf'l OF CKRTAIX BIRDS. 91 



possessor. There is not, liowever, in .ill cases a relationship 

 which is plainly to be recognised between differences in diet and 

 differences in the intestinal part of the alimentary tract, and on 

 the other hand a totally different diet sometimes coincides with a 

 close similarity in the intestinal convolutions. Phylogenetic 

 I'elationship appears to me to have much more to do with these 

 similai-ities and differences in the gut. Furthermore, the way in 

 which the intestinal tract is modified in accordance with the diet, 

 when it does .appear to be so modified, seems to have pursued a 

 <liSerent path in different groups in some cases. Of fi.sh-eating 

 birds, for instance, the general idea is that the gut is long, and 

 that undoubtedly is the case with the Penguin and the Cormorant- 

 Pelican group. But then in these groups no representatives a,re 

 known which are not fish-eaters. Directly we come to the 

 consideration of groups of birds which contain fish-eating genera 

 and genera whose food is not fish, we are sometimes met by a 

 totally diflerent state of afiairs. 



According to the statistics collected by Mr. Newstead*, the 

 Terns (of three species) a,re exclusively fish-eaters. Yet their gut 

 is not markedly and indeed hardly at ail different from that 

 of the Avocet, which devours aquatic insects, and some other 

 Limicolfe which select a similar diet. The .Kingfisher {Alcedo 

 ispida), which is, according to the same authority, practically 

 entirely a fish-eater, has a gut which is very like that of the 

 omnivorous Corvines, and has, moreover, a much shorter spiral 

 jejunum than in the differently feeding Halcyon sancta. The 

 Toucans t are mainly fruit-eaters, though, like so many birds, 

 they will vary this diet with animal food. And yet their intes- 

 tinal tract differs very little from that of Podargus, which is 

 presumably not at all a fruit-eater, but subsists entirely upon 

 insects and other animals. Again, the Touracous X are fruit- 

 eating birds ; but their gxit is like that of a vast series of Pico- 

 passerine birds which feed upon all kinds of food. 



In asserting that the gut is short in all purely frugivorous and 

 insectivoi'ous birds. Dr. Gadow practically admits how little stress 

 can be laid upon the relationship between length of gut and the 

 nature of the food. For the nature of the diet in each case is as 

 different as possible. Nor can any general principles be stated as 

 to the complication of the gut in families of birds which live 

 differently. Thus the plan of the gut in Apteryx is practically 

 identical with that of the Gallinaceous birds, and the character 

 of the food differs. On the other hand, the pattern of the gut in 

 Accipitrine birds is not dissimilar to that of Owls, and here w^e 

 have a general similarity in diet. It is, in fact, not possible to lay 

 down general rules which have not copious exceptions. Many of 

 these exceptions can be gathered fi'om the foregoing pages. 



* Supplement to th(> .Journal of the noavd of A.cjricultuve, vol. xv. No. 9 (1908). 

 t Newton, ' A Diftion;ivy of Birds ' (Loudon, 1893), sub voce ■•Toucan." 

 J; Id. thirl. ^ " Tounicou." 

 ■ § Id. ibid., " Digestive .System.' 



