certain Genera of Conchifera. 



23 



Glauconome rugosa. Philippines. 



Mantle-margins plain^ united ; pedal opening anterior, rather 

 large. Siphons longer than the shell, moderately thick, united 

 nearly to their ends, retracted, by inversion at half-length, into 

 the branchial cavity, where they project beyond the centre of the 



a', a, adductor muscles; p, p, pedal muscles; r, reti'actor of siphons; 

 b, c, pedal opening. 



shell ; orifices fringed. Foot moderately large, thick, linguiform, 

 heeled; suspensor muscle attached close to, but distinct from, 

 the adductors. Palpi very large, broadly falciform. Gills two 

 on each side, long and plaited, rounded in front, the outer pair 

 shorter and furnished with a plaited dorsal flap. 



In G. carta the siphons are much shorter and more deeply 

 divdded; the branchial was introverted at its extremity in the 

 specimen examined. 



Anomia ephippium. 



Animal unsymmetrical ; mouth and byssus twisted to the 

 right side. Mantle quite open, except for a space of five lines at 

 the hinge; its margin double, shghtly fi-inged (no ocelli). Gills 

 two on each side, unsymmetrical (the right pair shortest in 

 front), very delicate, flat (destitute of internal partitions or gill- 

 tubes), crescent-shaped, tapering to a point and united poste- 

 riorly ; suspended by two falciform membranes (w) forming three 

 dorsal channels, the lateral incomplete ; outermost gill-laminse 

 free at the dorsal edge, and furnished with a broad reflected mar- 

 gin or supplementary gill (r, ?•) ; innermost lamin?e also unat- 

 tached, but united to each other throughout their length, the 

 united edges passing to the left side of the body in front. Mouth 

 on the under side, between the ligament and byssal plug. Lips 

 narrow, plain, longest on the right side, confluent with the gills ; 

 [palpi obsolete). Foot small, cylindrical, expanded at the end 

 and grooved, supported by two muscles from the left valve. 

 Byssus large, laminar, passing through a nearly complete fora- 

 men in the right mantle-lobe, and attached by a powerful muscle 



