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



Fig. 1. 



Fig. !.• — 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. 



A. Anal siphon. 

 Aa. Anterior adductor muscle. 

 Ap. Posterior adductor muscle. 



£. Byssus thread. 



C. Cerebral ganglion. 



Ce. Cerebral commissure. 

 CP. Cerebro-pedal commissure. 

 M. Basement-membrane of velum. 



O. (Esophagus. 



Pe. Pedal ganglion. 



PI. Pleural ganglion. 



P. Respiratory siphon. 

 Pff. Ganglion of respiratory nerve. 

 S. Stomach. 



SS. Sheath of crvstalline style. 



V. Visceral ganglion. 



Vi. Visceral commissure. 

 VC. Velar cavity. 



