ABBREVIATIONS. 



a. anus. 



aa. anterior adductor muscle. 



b. byssus. 



bg. byssal gland. 



bgr. byssal groove. 



bn. byssal notch. 



d. dissoconch. 



di. distal end. 



er. "ear." 



/. foot. 



fc. foot cleft. 



fg. foot groove. 



fl. flagellum. 



fr. foot retractor muscle. 



Q* gills. 



h. hinge line. 



ht. heart. 



i. intestine. 



ig. inner gills. 



1. liver. 



Ip. labial palps. 



ra. mantle. 



