oe BS es 
33 gina DAML UZ ~~ 
Cae fat er ey, 
VN ea a RS 
wee ~~ &. 
‘ Ve = , 
leas \ 
— 
Fig.33 Macoma secta; ap, anterior palp; es, excurrent siphon opening; f; 
foot; ig, inner demibranch of gill; 7s, incurrent siphon opening; mf, fold of mantle, 
mm, mantle muscle; og, outer demibranch of gill; pp, posterior palp; r, rectum; 
vms, visceral mass. 
Fig. 34 Monia machrochisma; b, point on mantle edge where waste is col- 
lected; bs, byssus; gl, gill of left side; gm, suspending membrane of gill; gr, gill 
of right side; mo, mouth; pa, posterior adductor; pg, proximal oral groove; sl, 
shell ligament; wf, white folds of mantle; other letters as in figure 33. 
Fig. 35 Monia machrochisma; gill ciliation; fb, free base of gill lamella; gm, 
suspending membrane of gill; wf, white folds of mantle; x, line on gill surface 
from which currents diverge. . 
662 
