[ 1-73 ] 



VI f. On the Intestinal Tract of Birds ; with Remarks on the Valuation and Nomen- 

 clature of Zoological Characters. By P. CHALMERS MITCHELL, M.A., D.Sc. Oxon., 

 F.L.S., F.Z.S., Lecturer on Biology at the London Hospital Medical College. 



(Plates 21-23.) 



Read 21st March, 1901. 



CONTENTS. 



Page 



Introduction 173 



The Tract in Palamedea cornuta as an Archecentric Type 175 



Valuation and Nomenclature of Characters 178 



SYSTEMATIC DESCRIPTION 182 



Ratitse 182 



Carinatas 184 



f Colymbiformes 184 



J. Sphenisciformes 186 



I Procellariiformes 188 



f Cicomiformes 189 



< Anserif'ormes 201 



[ Falconiformes 205 



Summary of the Pelargo-Colymbomorphino Brigade 213 



(" Tinamiformes 215 



I Galliformes 216 



1 Gruiformes 222 



[ Charadriiformes 230 



Summary of the Alectoromorphine Legion 240 



f Cuculiformes 242 



| Coraciiformes , 245 



( Passeriformes 252 



Summary of the Coraciomorphine Legion 256 



Summary of the Systematic Description 257 



Autonomic Nervous System 258 



Morphology of the Intestinal Tract 261 



MeckeFs Diverticulum 262 



Meckel's Tract , . . . 264 



Supra-duodenal Loop 265 



Colic Caeca 267 



Characters and Classification 27D 



Bibliography 273 



Explanation of the Plates 275 



INTRODUCTION. 



IN 1813, in one of a series of papers on the Solvent Glands and Gizzards of Birds, 

 Sir E. Home (15) gave a description and some measurements of the intestines in the 

 Ostrich, Emu, Cassowary, and Rhea; and in 1814 (16) the same author described the 

 course of the intestines and the form of the cseca in a number of birds, giving figures, in 

 which, however, the coils were represented as freed from their blood-vessels and mesen- 

 teries. In the second edition of the ' Le9ons ' Cuvier (5) described the arrangement of the 

 intestinal tract in some dozen birds and distinguished regions, as the " duodenal loop " ; 



SECOND SERIES. ZOOLOGY, VOL. VIII. 28 



