PLATE LXTV. 



Gmelin, in his edition of the Systema Naturae of Linnasus for Tellina 

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

 Linneeus considers as one of the most certain criteria, whereby 

 species are to be distinguished, Gualtieri mtniions, the Shells al- 

 luded to as " Muscidiis fiuviatilis, striatiis, suhjlavus pellucidas" 

 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 'I", rivalis being of a more oblique and sub- 

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

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

 in a more central manner. 



Dr. Maton has 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. 



