ANODON. 275 



sloping upwards, and forming an angle with the fore 

 part of the shell. In M. cygneus the base slopes 

 upwards; and M. incrassatus differs from them all 

 by its large exserted ligament, superior roughness of 

 the outside, and in having the posterior part, in a 

 slope from the umbones to the base, incrassated. 

 (Linn. Trans, xiii. 87.) 



The Abbe Dupuy divides the French species into 

 sections^ thus : 



a. Cygn&i. Shell very large, thin, with the mus- 

 cular scars scars slightly marked. 



1. A. cygnsea. 



/3. Ponderosa. Shell large, very thick, especially 

 in front, muscular scars deep. 



2. A. ponderosa, Dupuy, t. 1. f. 12. 3. A. 



Dupuyi, t. 17. f. 13. 4. A. subponderosa, 

 t. 17. f. 14. 5. A. Rossmassleriana, t. 18. 

 f. 14. 



7. Anatina. Shell small, generally shorter and 



thinner than the preceding, with the muscular 

 scars less deep. 

 6. A. anatina, t. 19. f. 13, 14.; t. 20. f. 20. 



7. A. piscinalis, t. 19. f. 17, 18. 8. A. 



scaladiana, t. 19. f. 12. 9. A. Kayii, t. 20. 



f. 22. 10. A. coartata, t. 20. f. 21. 11. 



A. Milletii, t. 21. f. 16. 



8. Hiantes Shell middle size or small ; valves 



more gaping on the lower front edge than the 

 preceding. 

 12. A. Gratelupeana, t. 17. f. 22. 



T 2 



