CONCHTFEEA. 



437 



Family VII. — Chamid^. 



Shell ineqiiivalve, thick, attached ; beaks sub-spiral ; ligara.ent 

 external ; hinge-teeth 2 in one valve, 1 in the other ; adductor 

 impressions large, reticulated ; pallial line simple. 



Animal with the mantle closed ; pedal and siphonal orifices 

 small, sub-equal ; foot very small ; gills two on each side, very 

 unequal, united posteriorly. 



Chama (Pliny), L. 



Example, C. macrophylla, PL XYIII., Figs. 8, 9. 



Synonym, Arcinella, Schum. 



Shell attached usually by the left umbo ; valves foliaceous, the 

 upper smallest ; hinge-tooth of free valve thick, curved, received 

 between two teeth, in the other; adductor impressions large, 

 oblong, the anterior encroaching on the hinge-tooth. 



Animal with the mantle-margins united by a curtain, with 

 two rows of tentacular filaments ; siphonal orifices wide apart, 

 branchial slightly prominent, fringed, anal with a simple valve ; 

 foot bent, or heeled ; liver occupying the umbo of the attached 

 valve only ; ovary extending into both mantle-lobes, as far a3 



Fig, 223. Right side. Fig. 224. Left side. 



Fig. ;i23. Right side, with the umbonal portion of the mantle removed. 

 Fig. 224. Left side, showing the relative extent of the liver and ovarium, 

 a, a, adductors ; to, pallial line ; <?, excnrrent orifice ; b, branchial ; /, foot and 

 pedal orifice ; p, posterior pedal muscle ; t, palpi ; g, gills (contracted) ; /, liver ; o. 

 ovarium ; d, dental lobes. 



the pallial line ; lips simple, palpi small and curled ; gills deeply 

 plaited, the outer pair much shorter and very narrow, furnished 

 with a free dorsal border, and united behind to each other, and 

 to the mantle ; adductors each composed of two elements. 



