368 CANCEL! ARIAD^. 



We have given a drawing, at plate CV. (f. 1), of a 

 remarkable shell which was taken at Exmouth by Mr, 

 Clark. It appears to differ from some of the varieties of 

 tuherculare in no other respect than in the absence of the 

 central row of tubercles on each whorl ; an important 

 feature, however, and one that, if constant, is perhaps of 

 specific value. As the specimen is much worn, and has its 

 mouth broken, we nevertheless think it advisable to refer it 

 provisionally to the present species. It is a strong shell, 

 with the tubercles connected by longitudinal riblets, so 

 much so, indeed, that the earlier turns might almost be 

 termed cancellated. In case it prove eventually to be 

 distinct, we propose to name it Cerithiopsis Clarkii after its 

 distinguished discovei'er. 



