40 



wholly of a dirty white. Inficle white : hinge furnifliecl witJi 

 four teeth in each valve, but the outer one above the cordi- 

 form depreffion in one valve is obfolete, or formed only by 

 a cavity for the reception of the correiponding tooth in the 

 oppofite valve: the margin is finely crenulated. Length 

 more than an inch ; breadth above an inch and a quarter. 



The above defcription is taken from a fhell in the cabinet 

 of Mr. Laskey, who favoured us with it for the purpofe, and 

 at the fame time allured us he took it by dredging, off' the 

 ifle of My, in the Frith of Forth, in the year 1804. 



Should this prove to be the fpecies defcribed by the author 

 of the BritiJljJJjells, we learn no more oi its habitat than wliat 

 he quotes from Da Costa, who defcribed his fliell from a 

 fpecimen in the colleftion of DoSlor Fothergill, which was 

 from the weftern coaft. 



In our cabinet is a fingle valve of about half the fize of 

 that before defcribed, which was found in DevonJJnre ; in 

 this the longitudinal jlricc is evident by the afllltance of a 

 lens in (hefulci between the tranfverfe ridges. 



UtFLEXA. Shell fub-orbicular, furniflied with numerous thin laminal 

 ridges, which are reflected, and on the cartilage fide are 

 very fharp, more elevated, and undulated, and turn forwards 

 or in a contrary diredlion to thofe on the other parts : thcfe 

 ridges are not quite regular and equi-diftant, for fometimes 

 a fmall intermediate one is obferved, or two larger lamiiue 



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