ANATOMY OF THE CLAM. 



227 



gills, where the embryos in some species partially develop. 



Impregnation probably takes place within the branchial 



chamber, the spermatozoa being 

 swept in with the respiratory 

 current, and coming in contact 

 with the eggs as they are dis- 

 charged. 



An excellent general view of 

 the relation of parts to the 

 body -walls and shell may be 

 seen by hardening a clam, or 

 better a fresh -water mussel, 

 Unio (see Fig. 155, D) in alco- 

 Fig. 160. -Pedal ganglia and oto- hoi, and then making trans- 



cyste (ears) of the clam, magnified 10 VPVQ p confirms \ eppfinn ran 



diameters, d, pedal ganglia ; e, pedal VCrSC S6C IIS. A. SC 



commissures;/, line of union of gan- K , flo'lfod off ill water aild 6X- 

 glia; <7, nerve from commissure to 



muscles of loot ; A, auditory nerve ; i, amilied With a leilS. The per- 



otocyst ; k, nerves from ganglia to r 



the pedal muscles. Drawn b> vv K. feet bilateral symmetry of parts 



Brooks. J J 



will thus be seen. 

 The above description will Answer for the majority oi la- 



ft 



. 161. Lima Mans, flying through the water, its long numerous filaments ex- 

 tended. From Brehm's ' Thierlehen." 



mellibranchiate mollusks ; in the oyster (Ostrea) or in Ano- 



