CORBULA 



TESTA ioaequivalvis, siibsequiiatera, transversa, 

 pleruraque gibbosa, clausa. Dens eardinaiis in 

 utraque valva, conicus, ciirvus, (ascendensj 

 foveola lateral! adjecta. Lig amentum internum, 

 denti valvar minoris, foveolse majoris afiixum* 

 Impressiones musculares duae, laterales, distan- 

 tes, subirreguiares. Impressio pallii adhaerentis 

 musculi subintegra. 



Placed by Linneans among the Mi/cv^ but well distin- 

 guished from them by being closed and not gaping, as 

 well as by other characters which we shall detail as we 

 proceed to give the description of this Genus ; but we 

 wish in the first place to draw the attention of naturalists 

 to a small river shell, named Mi/a labiata, by Maton, in 

 the Trans, of the Linn. Soc./' vol. viii., which, how- 

 ever, nearly ft may in many respects resemble a Corbula, 

 we still hesitate to unite with that Genus, though we do 

 not find characters of sufficient importaivce to warrant its 

 absolute separation, and in company with its fossil con- 

 geners from undoubtedly fresh water formations, consti- 

 tuting a new Genus. It is more compressed than the 

 Corbulee ; its larger valve only exceeds the other at the 

 upper edge: it is more acuminated anteriorly; it has 

 two small teeth in the hinge of its larger valve, with an 

 internal and central ligament, and a small accessary 

 muscular impression is placed immediately below each of 

 the principal ones. In most of these respects the fossil 

 species, which forms a very thin stratum, apparently of 

 very considerable extent above the upper fresh water 



