GILLS 



387 



bodies on each side between the visceral mass and the 

 mantle : we have thus a right and a left outer, and a right 

 and a kft inner gill (Fig. 95, ext. gl, int. gl.). Seen from 







-p - c ? r — ■- 



^ .V P i; 



^ " w y ^ ' 



Q E' 



°~5 215 5 5; 



-(^■^ f= ^ OJ 1) 



the surface (Fig. 93), each gill presents a delicate double 

 striation, being marked by faint lines running parallel with, 

 and by more pronounced lines running at right angles to, 



eg? 



