252 Mr. C. P. Sigerfoos on the Pholadidaj. 



Fig. 1. 



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Fig. 2. 



Fig. 1. — Longitudinal vertical section of newly attached ship-worm. 



The disintegrated cells of the velum are not shown. 

 Fig. 2. — Outlines of the ganglia of nervous system, dorsal view. Only 



commissural nerves are shown. 



Pedal ganglion. 

 Pleural ganglion. 

 Respiratory siphon. 

 Ganglion of respiratory nerve. 

 Stomach. 



Sheath of crystalline style. 

 Visceral ganglion. 

 Visceral commissure. 

 Velar cavity. 



