31 
8. Adacna. 
1. A. laeviuscula (fig. 14). 
Fig. 14. — Adacna Iceviuscula. 
§§§ Siphons very large, united at the base j upper part free, ringed. 
9. Macha. 
1. M. strigillatus, t. 342. f. 5. 
2. *M. candidus, t. 344. f. 1. 
10. Azor. 
1. A. coarctatus, t. 344. f. 4. 
§§§§ Siphons elongate, cylindrical . 
11. Tagelus. 
1 . T. viridi-seneus ?, t. 342. f. 1 . 
Suborder II. Heteroconch^e. 
Body not symmetrical. Valves unequal. Cartilage internal, in 
a pit. Hinge simple. Pedal opening inferior. Living lying on 
the side in sand or mud. 
Fam. 6. Myadce. 
Siphons elongate, united, covered with a horny periostraca. Gills 
two on each side, dependent. Lips small. Shell porcellanous. 
Hinge toothless. Cartilage-pit in a hollow in one, and a concavity 
in the umbonal surface of the other valve. 
1. Mya. 
1. M. truncata, t. 348. f. 2, 5 (fig. 15). 
Fig. 15. — Mya truncata. 
