CONCHYLIA— 2)/rHyi?^. 5. 28 



In rocks in the Isle of Sky. 



We are unacquainted with this shell, except from the description 

 of Montagu It appears to resemble the Saxicava rugosa, but the 

 anterior side is more dilated, and the strias are more or less raised 

 into ridges. 



^ HIATELLA— D^(7D/iV. 



Testa transversa incequivalvis, incequilateralis, margine supero vel latere 

 antico hiante. Cardo dente unico inter duos obsoletos penetrante : 

 lateralihus nullis. Ligamentum externum. 



Shell transverse, inequivalve, inequilateral, open at the upper mar- 

 gin or anterior end. Hinge with a single tooth in one valve 

 closing between two obscure ones in the other : lateral teeth 

 none. Ligament external. 



Of the two subsequent species we have not thought it necessary 

 to form different genera, merely from the variation in their habitats 

 and openings. The first is, we believe, generally attached to the 

 rugged cavities of oysters, and the roots of Fuci, by a strong bys- 

 sus issuing from the opening in the upper or front margin. The 

 other is imbedded in rocks, and like most of the rock shells opens 

 at the anterior or smaller end. 



