440 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



decision can be had as to their relations and the number of valid 

 groups. Since Sowerby's shell is stated to have come from South 

 Africa, there can be little doubt that the identification of Krauss is 

 correct. It is in the highest degree improbable that Meuschen in 

 1782 had any opportunity of knowing the very rare Magellanic 

 species called megatrema by Orbigny; but South African shells 

 were then abundant in Europe, owing to the trade with the Indies 

 by way of the Cape of Good Hope. 



Doctor Pilsbry in the Manual places Jiiantula ( = megatrema) 

 under Fissurellidea; aperta Sowerby, under PupiUaea; scutellum 

 (Meuschen) Gmelin, under Megatebennus subgenus AmblycJiilepas; 

 with reasonable justification, but the bare shells, especially if a 

 little worn, can hardly be told apart. 



The last genus of the group referred to is Cemoria, cited from 

 Leach's proof sheets, but luckily anticipated by Lowe's Puncturella, 

 based on F. noachina of Linnaeus. 



