NATURAL SCIENCES OF PHILADELPHIA. 249 



G. Pacifica, C. B. Adams, Panama Shells, 215. 1851. 

 H. & A. Adams, Genera, iii. t. 115, f. 7, a. b. 



Panama; Mazatlan. 

 G. parva, C. B. Adams, Proc. Bost. Soc. Nat. Hist. ii. 9. 1845. 



Jamaica. 

 G. Pfeifferi, Philippi, Zeit. fiir Malak. 133. 1848. 



Cuba. 

 G. varians, Carpenter, Mazat. Cat. 83. 1857. 



Ilazatlan. 



Genus MIODON, Carpenter. 

 Ann. Mag. Nat. Hist. xiv. 424. 1864. 

 1. M. prolongatus, Carpenter, loc. cit. 



Straits of Fuca to Monterey, Gal. 



Genus CRASS ATELLA, Lamarck. 1 

 Prodr. Syst. 1799. 

 Ptychomya, Agassiz (fossil), Etnd. Crit. 3d liv. 1842. 

 Paphia, Roissy (not Lam. or Fabr.), Moll. vi. 346. 1805. 



C. Adeline, Tryon, Proc. A. N. S. 1872. 

 C. Antillarum, Reeve, Zool. Proc. 44. 1842. 

 Conch. Icon. sp. 8. 1843. 

 G. rostrata, Chenu 111. Conch. 



Isl. Margarita, ( IF. 2. ?) 

 C. aurora, Adams and Angas, Cool. Proc. 426, t. 37, f. 15. 1863. 



Tasmania. 

 C. Banksii, Adams and Angas, Zool. Proc. 427, t. 37, f. 16. 1863. 



Tasmania. 

 C. bellula, A. Adams, Zool. Proc. 95. 1852. 



New Zealand, 

 C. castanea, Reeve, Zool. Proc. 42. 1842. 

 Conch. Icon. spec. 3. 1843. 



Australia. 

 C. compressa, Adams and Reeve, Yoy. Samarang, 82, t. 23, f. 10. 

 1850. 



Gorea. 



1 I think that a considerable reduction of species is necessary in this 

 genus ; but, unfortunately, I have not enough specimens at hand to make 

 satisfactory comparisons. The species appear to vary so much in form, 

 sculpture, and color, that identification, in many cases, is entirely arbi- 

 trary. 



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