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Comparative Morphology of Chordates 



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Fig. 569. Teeth of sheep (Ovis aries). (c) Canines; (i) incisors; (m) molars; 

 (pm) premolars. (From Wiedersheim : "Comparative Anatomy of Vertebra tes." By 

 permission of The Macmillan Company, publishers.) 



Fig. 570. Stomach of ruminant opened to show internal structure, (a) Esopha- 

 gus; (b) rumen or paunch; (c) reticulum or honeycomb bag; (d) psalterium or many- 

 plies; (e) abomasum or reed; (/) duodenum. (Courtesy, Flower and Lydekker: 

 "Introduction to the Study of Mammals," London, A. & C. Black, Ltd.) 



