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SOLEN, Linn. 



Gen. Char. Equivalved, very inequilateral and 

 transverse, straight, gaping at both ends; supe- 

 rior and inferior margins parallel ; umbones 

 nearly close to the anterior extremity. Hinge 

 with one direct tooth in each valve ; ligament 

 external, strong, attached to long- linear fulcra. 

 Epidermis thick. Muscular impressions two, 

 the anterior wide, elongated, pamllel to the 

 fulcrum ; the other submarginal, distant from 

 the beaks. Palleal impression with a deep 

 sinus. Epidermis thick. 

 Animal with the mantle closed except at the 

 extremities. 



1 HE division of the genus Solen of Linnaeus into five genera, 

 and the discovery of several species in a fossil state of four 

 of the genera, have rendered it necessary to give an amended 

 generic character. Amidst the various opinions as to the 

 number of genera into which it should be divided, the sepa- 

 ration of all those shells whose umbones are not quite late- 

 ral is most general; and next, the presence of lateral teeth 

 in the hinge is allowed as sufficient to distinguish another 

 group, which is however very artificial, and the genus 

 Solen is thus limited as in the above Gen. Char.; but it 

 may hereafter be further divided into two subgenera, one 

 of them being characterized by a longitudinal furrow near 

 the anterior margin, which the other does not possess. The 



