COITCHrFERA. 



437 



Family YII. — Chamid^. 



Shell inequivalve, thick, attaclied ; beaks sub.-spiral ; ligament 

 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, PI. XyilL, Pigs. 8, 9. 



Synonym, Aroinella, 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, witl^ 

 two rows of tentacular filaments ; siphonal orifices wide apart, 

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

 foot bent, or heeled ; liver occuj)ying the umbo of the attached 

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



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



Fig. 223. Eight side, ss^th the umbonal portion of the mantle removed. 

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

 a, a, adductors ; m, pallial line ; e, excurrent orifice ; b, branchial ; /, foot and 

 pedal orifice ; p, posterior p^dal muscle ; t, palpi ; g, gills (contracted) ; I, 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. 



