XXVIII 



SHELL 



35 1 



.Jb.ad 



FIG. 92. A, interior of right valve of Anodonta, showing the various 

 impressions produced by the muscles shown in B : h. /, hinge-line ;//. /. 

 pallial line. 



B, the animal removed from the shell and seen from- the left side. 



a. ad, anterior adductor ; a. r, anterior retractor ; d. g, digestive gland, 

 seen through mantle ; ex. y sph, exhalant siphon ; ft, foot " gl, gills, seen 

 through mantle ; in. sph, inhalant siphon ; kd, kidney, seen through 

 mantle ; k. o, Keber's organ, seen through mantle ; w,"mantle ; p. ad, 

 posterior adductor ; pc, pericardium, seen through mantle ; pi. m, pallial 

 muscles ; /. r, posterior retractor ; prc, protractor. 



(From Parker and Haswell's Zoology. ) 



short distance from it, is a delicate streak (pi. /) caused by 

 the insertion into the shell of muscular fibres from the edge* 

 of the mantle : the streak is hence called the pallial line. 



