26 On the Animals of certain Genera of Conchifera. 



Scallops. Carotia (Hemiplacuna) is a Placuna with the hinge 

 and byssus of Anomia ; Placunomia has no pedal muscle, like 

 Placuna sella ; whilst Anomia pernoides has an anterior pedal sac 

 in each valve, as pointed out by Dr. Gray. 



Anatina subrostrata. Philippines. 



Mantle-margins united ; no ventral orifice ; pedal opening quite 

 anterior, minute. Siphons united, thick, not entirely retractile 

 into the shell, covered with rugose epidermis; orifices small 



a, a', adductors ; g, single gill ; o, cavity of ossicle ; ?, liver ; A, palpi : the 

 termination of the alimentary canal in the exhalent siphon is indicated 

 by dotted hnes. 



(fringed?). Foot very small, compressed. Gills one on each 

 side, long, narrow, very thick and deeply plaited, furrowed at 

 the lower edge, not continued into the branchial siphon ; dorsal 

 border free, nearly as wide as the gill. Palpi very long, narrow, 

 free, striated inside. 



Modiolarca trapezina. Falkland Islands. 

 Mantle-lobes united, leaving only three small, subequal ori- 



a, a', adductors ; p, p', pedal muscles ; /, pedal opening ; /, liver; the gill- 

 tubes are distended with spawn. 



fices^ the interspaces with two rows of cirri ; branchial opening 



