PLATE LXIV. 



Gmclin, in his edition of the Systema Naturae of Linnaeus for Tellina 

 cornea, though it evidently differs from the latter in shape, which 

 Linnaeus considers as one of the most certain criteria, whereby 

 species are to be distinguished. Gualtieri mentions the Shells al- 

 luded to as " Musculus fluviatilis, striatus, subflavus pellucidus" 

 which is a vague and imperfect description, and by no means sufficient 

 to shew in what respect it differs from T. cornea." The difference 

 consists chiefly in the T. rivalis being of a more oblique and sub- 

 ovated form, and in having the hinge near one end ; T. cornea is 

 somewhat globose, and in particular has the hinge and beaks placed 

 in a more central manner. 



Dr. Matonhas generally found Tellina rivalis on chalky parts of the 

 bed of the river' Avon, and in rivulets communicating with it near 

 Salisbury ; but has never seen it in any considerable abundance. He 

 conceives, that if diligently sought after, it may be discovered in most 

 rivers and streams which are inhabited by Tellina cornea* 



