278 



COMPARATIVE ANATOMY. 



-r* 



FIG. 222. HEAKT.S OF VARIOUS FISHES A, OF THE HAMMER-HEADED SHARK 

 (Zygeena malleus) ; B, OF Silurus glanis ; C, OF A SELACHIAN, CUT OPEN. 



In A and B, A, A, atria ; a, a (in A), auricular appendages ; V, ventricle ; 13a, bulbus 



arteriosus ; tr, ventral aorta. 

 In C, a, a, indicate the atrio-ventricular valves, and b, the valves in the conns 



arteriosus (Go) ; A, atrium ; V, ventricle. 



ventricle (Fig. 222, V] and an atrium (A), the latter receiving 

 its blood from a sinus venosus, and being laterally expanded 

 to form the appendices auriculae (A, a, a). 



