2U 



DR. P. CHALMERS MITCHELL ON THE 



that fouud among the Cuculiclse. In these, as we have seen, the tendency is for tlie 

 anterior portion of Meckel's tract to be produced into two loops, and this mode of 

 apoceutricity is typical of Coraciiform birds. The reduced gut of the Musophagidje 

 might have come from any simple source. The Psittaci live largely on hard grains and 



Fis. 01. 



Intestinal Tract of Strinr/ops hahroplilus. 



a, h, c and S.D.F. are the four loops of Meckel's Tract typical of the Psittaci ; a, h, and c bcin?; 



here subdivided, while S.D.F. is a supra-diiodcnal loop. 



seeds, and this habit, together with tlie large size of many of the forms, has no doubt 

 greatly added to the length of the gut and helped to disguise its morphological form. 

 That conformation is markedly apocentrie, as shown by the complicated folding of the 

 loops, the length of the loops, the individuality of the supra-duodenal loop, and the 

 absence of ca'ca. No doubt such a type might have been derived independently from 

 any of the more archecentric forms, from, for instance, some of the simpler Galli, as lias 

 Ijeen suggested, but it is equally easy and perhaps more natural to derive the Psittacine 

 type from that occurring in the simpler Coraciiform birds. 



