n,22 Letters, E.rtracls, Notices, b;c. 



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JVie Intestin.nl Tract of Birds. — At the Linnean Society's 

 meeting on the 21st of JNlarch last, Mr. P. Chalmers Mitchell, 

 F.Z.S., read a paper entitled " The Anatomy and Morphology 

 of the Intestinal Tract in Birds; with Reniai'ks on the No- 

 menclature and A'al nation of Zoological Characters," He 

 described the various conformations of the intestinal tract in 

 birds, his material consisting of many hundreds of specimens 

 belonging to all the living Ratitte as well as to all the Orders 

 and Suborders and nearly all the Families of Carinatxe. He 

 discussed the morphology of the tract, distinguishing, in 

 their adult anatomy and in their relation to the embryonic 

 metamerism, the duodenum, Meckel's tract, and th.e rectum. 

 He described the nature and distribution of the changes in 

 these organs and in Meckel's diverticulum and the colic 

 caeca, and gave an account of a remarkable and hitherto 

 undescribed series of nervous structures belonging to the 

 autonomic nervous system, apparently peculiar to birds. In 

 discussing the relation of the series of facts described to the 

 Systems of Avian classification, he insisted on the piimary 

 necessity of valuing characters as Archicentric or Apucontric, 

 primitive or specialized, A common possession of a character 

 in either the Archicentric or Apoccntric condition was no 



