79 



Fig. 58. — Section of Anodon^la, showing the digestive tube: m, Mouth; 

 g, gullet; /, Hver; s, stomach; r, i, intestine; a, anus; p, pericardium; k, 

 kidney; s.c, chamber above the gills. (Furneaux.) 



Fig. 59. — Anodor/ta, lying in one valve, with upper lobe of the mantle 

 removed: p, Pericardium; A-, kidney; p.r., posterior retractor muscle; 

 p.a., posterior adductor muscle; a.a., anterior adductor muscle; a.r., anterior 

 retractor muscle; p.p., protractor pedis muscle; a, anus; e.s., exhalent 

 siphon; i.s., inhalent siphon; l.m., cut edge of the mantle; o.g., outer gill- 

 plate; m.l., mantle lobe; v.g., inner gill-plate; v, internal organs; /, foot; 

 I. p., labial palps; Z, liver; p.l., pallial line. (Furneaux.) 



Fresh-water mussels (Figs. 58, 59) or clams of our ponds, lakes, and 

 streams have firm leaf-like gills and two nearly equal adductor muscles. 



