PICAEI^ 



IV. — The caeca are two little blind tubes spriDging from the 

 intestine at the commencement of the rectum or hinder part of the 

 gut. In a broad way they are best developed in purely herbivorous 

 birds, and small or short in meat- and fruit-eaters ; sometimes they 

 are entirely absent. 



Pig. 5. — Base of the skull of Serpentarius secretarius, showing the desmo- 

 guathous arrangement of the palate bones, the maxillo -palatines being coalesced 

 across the middle line : tot^:), maxillo-palatines ; pa, palatine : sph.r, sphenoidal 

 rostrum ; ptg, pterygoid ; b.ptg.pr, basi-pterygoid process of the basi-sphenoid ; 

 b.sph, basi-sphenoid. 



V. — Huxley first pointed out the value of the arrangement of 

 bones of the palate as an important character in classification. He 

 distinguished four types of modifications as follows : — 



