FAMILY 7. NYMPHACEA. 83 



The shell of Donax is so strongly characterized by its short trun- 

 cated wedge-shaped form, that the genus remains nearly as entire as in 

 the time of Linnaeus. 



It may be described as transverse, equivalve, inequilateral, with the an- 

 terior side very short and obtuse, and the valves more or less crenulated 

 round the inner margin. There are two cardinal teeth in one valve and 

 one in the other, bifid superiorly ; there are also one or two lateral teeth 

 in both valves, more or less distant from each other. The ligament is 

 external, short, and generally bipartite, a portion of it being situated 

 under the umbones ; and there is a large sinus observable in the muscu- 

 lar impression of the mantle. 



Examples. 



PI. LX. Fig. 1 . 



Donax scortum, Linnaeus, Syst. Nat., p. 1126. Lamarck, Anim. sans 

 vert., new edit., vol. vi. p. 239. De Blainville, Manuel de Malaco- 

 logie, pi. 71. f. 1. 



Donax pubescens (testa junior), Lamarck. 



PL LX. Fig. 2. 



Donax cuneata, Linnaeus, Syst. Nat., p. 1127. Lamarck, Anim. sans 

 vert., new edit., vol. vi. p. 240. Enc. Me'th., pi. 261. f. 5. 



PL LX. Fig. 3. 



Donax trunculus, Linnaeus, Syst. Nat., p. 1 127. Lamarck, Anim. sans 

 vert., new edit., vol. vi. p. 248. Enc. Meth., pi. 262. f. 1. 



PL LX. Fig. 4. 



Donax deltoides, Lamarck, Anim. sans vert., new edit., vol. vi. p. 241. 



Sowerby, Genera of Shells, No. 10. 

 Donax laevigata ? Dillwyn. 



m 2 



