25O OILMAN A. DREW. 



PLATE XIX. 



FIG. 5. Outer surface of the left lobe of the mantle showing the arrangement of 

 blood vessels. Two thirds natural size. 



FIG. 6. Animal as seen from the left side with the left shell valve and mantle lobe 

 removed. Drawn to show the nervous system. Two thirds natural size. 



apa, anterior pallial artery; apn, anterior pallial nerve; bn, branchial nerve; 

 cc, cerebral commissure ; eg, cerebral ganglion ; cpn, circumpallial nerve ; cvc, cere- 

 bro-visceral connective; of, otocyst ; pa, posterior adductor muscle (anterior por- 

 tion) ; pa' , posterior adductor muscle (posterior portion) ; pg, pedal ganglion ; ppa, 

 posterior pallial artery ; ppn, posterior pallial nerve ; pv, pallial vein ; vg, visceral 

 ganglion. 



