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TEXTBOOK OF ZOOLOGY 



giving branches to the viscera and body wall. There is no renal 

 portal system; the caudal vein simply divides, giving one part to 

 each posterior cardinal vein. 



— DORSAL AORTA 



5TH.R. EFFERENT 

 BRANCHIAL A. 



4TH. R. AFFERENT 

 BRANCHIAL A. 



VENTRAL AORTA 



INFERIOR JUGULAR V. 



R. JUGULAR VEIN 



VENTRICLE 



SINUS VENOSUS 



ATRIUM 



HEPATIC V. 



R. POST CARDINAL V, 



RENAL A. 



RENAL V, 



INTESTINAL V. 



INTESTINAL A. 



CAUOAL VEIN 

 CAUDAL ARTERY 



Fig. 225. — Diagram of oblique ventrolateral view of heart, arteries, and veins 

 of lamprey. Arrows indicate direction of flow of blood. (Drawn by Titus C. 

 Evans. ) 



The seven pairs of gills and respiratory tube constitute the prin- 

 cipal features of the respiratory system of this animal. When the 



