356 Dr. W. C. M'Intosh on the Mollusca of St. Andrews. 



Fam. 18. Anatinidse, D'Orbigny. 



Genus Thracia, Leach. 



Thracia papyraceay Poli. Op. cit. iii. p. 36, v. pi. 48. f. 4 & 4 a. 



Common on the sandy ground off the West Sands, and 

 cast ashore plentifully after storms. 



Fam. 19. Corbulidse, Fleming. 



Genus 3. Corbula, Braguifere. 



Corhula gihha^ Olivi. Op. cit. iii. p. 56, v. pi. 49. f. 6. 



Off the East Rocks in a few fathoms, and on the beach after 

 storms ; good specimens are also procured from the fishing- 

 boats. 



Fam. 20. Myidse, Fleming. 



Genus Mya, L. 



Mya arenaria, L. Op>. cit. n\. p. 64, v. pi. 50. f. 1. 



Frequent in the muddy sand at the mouth of the Eden. 

 Distorted valves are common. 



Mya truncata, L. Op. cit. iii. p. 6Q, v. pi. 50. f. 2. 



bundant 

 after storms. 



Abundant off the mouth of the Eden, and on the beach 



Fam, 21. Saxicavidae, Swainson. 



Genus 2. Saxicava, Fleurian de Bellevue. 



Saxicava rugosa^ L. Op), cit. iii. p. 81, v. pi. 51. f. 3 & 4. 



Common, at low- water mark amongst the rocks in crevices 

 and holes in sandstone and shale, as well as inside empty 

 limpet-shells and Balwii. Often firmly adherent to its cavity 

 by a byssus. 



Fam. 23. Pholadidae, Gray. 



Genus 1. Pholas, Lister. 



Pkolas Candida, L. Op. cit. iii. p. 107, v. pi. 52, f, 2. 



Rarely found in shale at the Castle Rocks ; commonly met 

 with on the beach after storms, sometimes in a perfect con- 

 dition. 



