18 
large, oblong, simple. Gills, two pairs, moderate, subequal, united 
together behind. Lips elongate, lanceolate. Foot compressed, 
small, quadrate, angular at each end. Shell solid, covered with a 
hard, olive, polished periostraea. Cardinal teeth 3 • 3, diverging. 
Lateral teeth compressed. Siphonal inflection none. 
1. Corbicula. 
1. C. limosa, t. 359. f. 4. 
Fam. 6. Cyclasidce. 
Mantle lobes united at each end. Pedal opening moderate. Foot 
compressed, lanceolate. Siphons united at the base, separate, di- 
verging at the tip. Apertures bearded. Shell oblong. Cardinal 
teeth 2 * 2. Lateral teeth elongate, compressed, smooth. 
1. Sph^erium. 
1. S. rivicola, t. 359. f. 7. 
2. S. corneum, t. 317. f. 4, t. 357. f- 11, t. 359. f. 3. 
3. S. catyculatum, t. 349. f. 2, t. 359. f. 6. 
Fam. 7- Cyrenelladi e. 
Mantle lobes free beneath, united at each end. Siphons two, 
elongate, united, contractile. Lips elongate. Foot subcylindrical, 
club-shaped. Gills two on each side. Shell oblong, roundish, ven- 
tricose, covered with a hard olive periostraea. Siphonal inflection 
none. — Ann. fy Mag. N. H. xi. 1853, 39. 
1. Cyrenoida. 
1. C. Dupontia, t. 347- f. 1, 2, 3. 
Fam. 8. Mysiadce. 
Pedal opening moderate, inferior. Siphons none ; anal opening 
linear, with two semilunar lateral valves; inhalent small, round, 
fringed. Gills two on each side. Lips four, moderate. Foot com- 
pressed, lanceolate. 
1. Mysia. 
1. M. rotundata, t. 358. f. 2. 
2. M. ? (Philippines) (flg. 3). 
Fig. 3 . — Mysia ? (Philippines). 
foot, p, palpi. I, liver, b-c, pedal opening. 
