MORPHOLOGY OF LAMELLI BRANCHIATE MOLLUSKS. 
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Plate XCI. 
Solenomya velum : 
Fig. 77. Cross-section of two gill plates ; glc, gland cells ; ve, ciliated, columnar cells of thickened 
ventral edge of plate ; ch, chitinous rods, lined interiorly hy endothelium ; w, cells of interior 
walls of plate. 
Yoldia limatula : 
Fig. 78. Diagrammatic view of ventral edges of gill plates ; p, ventral edges of plates ; gr, ventral 
groove; cj, ciliated junction between plates. 
Fig. 79. Vertical section across gill plate; e, frontal epithelium hearing very large cilia; r, ridge of 
cells forming first compound straining line ; t, cells forming second compound straining line ; 
ch, chitin, inclosing b, a blood-channel lined hy endothelial cells ; s, blood space of interior 
of plate, bridged across by numerous branching lacunar cells, lac; f, folds in wall of plate ; 
d, blood space at dorsal edge of plate. 
Fig. 80. Cross-section of dorsal ends of plates of gill ; lac, numerous lacunar cells ; ep, epithelium 
on surface of supporting membrane of gills ; m, muscles of same. 
Fig. 81. Diagram of plates of gills showing planes of sections; a, plane of Fig. 79; b, of Fig. 82; 
c, of Fig. 80; d, of Fig. 48, PL lxxxvi. 
Fig. 82. Sections of plates of gill, Yoldia, in plane /, Fig. 81, showing lines of ciliated junction, 
cj ; e, lateral edge of plates; s, space between edges of plates where ciliation is absent; lac, 
lacunar tissue ; ep, epithelium of supporting membrane of gills ; m, muscles of same. 
Plate XCII. 
Pecten ir radians — Scallop : 
Fig. 83. Cross-section of single filament, gill of Pecten ; /, ciliated frontal epithelium; glc, gland 
cells; pg, pigment in region of gland cells; If l, cells of compound straining line; ch, ehitin; 
p, septum of filament showing nucleus. 
Fig. 84. Diagram of portions of three filaments of gill, to show nature of ciliated spurs, cs, which 
form means of inter filamentar union; fil, filament. 
Anornia simplex : 
Fig. 85. Inner ends of filaments of Anomia, to show gland cells. 
Pecten irradians — Scallop : 
Fig. 86. Cross-section of gill of Pecten ; ra, reentering angle of gill folds ; sa, filament at salient 
angle of gill fold; ch, chitin of modified filament of reentering angle; If l, straining line of 
modified filament; be, blood space of modified filament; w, walls of modified filament, 
forming interlainellar union ; lac, lacunar tissues ; cs, ciliated spurs connecting filaments. 
Plate XCIII. 
Mytilus ednlis — Common mussel : 
Fig. 87. Siphonal region of mantle in Mytilus seen from behind; co, cloacal opening; brm, branchial 
membrane; me, mantle edge. 
Fig. 88. Same, seen from in front; co, cloacal opening; og, outer gill; brm, branchial membrane; 
m, mantle. 
Ostrea virginiana — Oyster : 
Fig. 89. Posterior region of mantle in Ostrea, seen from behind; r, rectum, opening into upper end 
of cloacal chamber; brp, concrescence of mantle edges above gills; ig, inner gill; og, outer** 
gill ; me, mantle edge. 
Venus mercenaria — Quahog : 
Fig. 90. Posterior region of mantle in Venus, view of base of siphons ; og, outer gill ; bm, branchial 
membrane ; me, mantle edge. 
Solenomya velum : 
Fig. 91. Gills of one side of body in Solenomya; m, supporting membrane; gr, groove on median 
line opposite supporting membrane. 
Yoldia limatula : 
Fig. 92. Gills of one side of body in Yoldia; m, supporting membrane; gr, groove on midline of 
ventral surface. 
