PLATE CLXX. 



prominent in the middle, but in approaching each extremity become 

 suddenly obtuse, and are then continued in an attenuated ridge, par- 

 ticularly as they extend towards the front of the shell, and thus 

 exactly corresponding with the definition of Linnaeus, " rugis 

 incrassatis, pube rugis attenuatis." On the contrary, in our 

 shell the ridges are nearly of an uniform thickness throughout, 

 sloping gradually with the depression of the shell behind, and only 

 terminating abruptly at the edge of the front, or fore part of the shell 

 where the valves appear obtuse : the outline of the shell is also very 

 ditFerent from Venus Paphia, the latter being more produced on. each 

 side than our Venus Fasciata. 



