BIVALVES — MYA. 
17 
Division Il.—Hinge callous, without teeth. 
Scientific Name. Locality. 
Edentula ------- Caspian Sea----+++-++:- 
Membranacea:-- Iceland --++-----+++++++> 
Norwegica--++-- Norway -+:++++*: ares 
Siliqua cette ee N. America --+-e-:---: 
Common Name. 
Toothless Gaper - 
Membraneous G. 
Norwegian do - 
Bean-pod -- do 
Division UI.—Hinge with teeth inserted into the opposite 
valve. 
The M. ponderosa, or M. crassa of some authors, with 
others in this division, are remarkable for their exces- 
sive weight and thickness; which is universally the 
case with those that are found in rapid rivers and 
cataracts. 
The M, margaritifera is famous for the production 
of fine pearls, and was formerly found in great quan- 
tities in the river Conway in Wales, and in Scotland. 
Scientific Name. Locality. 
Batava -------+- Dauube,Rivers of Hoiland 
Re: Kennet------+++-+-: 
Pictorum-------- European Rivers -+---+++ 
Ovata -----+-+-+ Rivers of England ---- - 
Radiata --------- Rivers of Malabar------- 
Ponderosa ------ Chinese Rivers --------- 
Complanata ---- North American Rivers: - 
Nodulosa ------- Rivers of North Europe: - 
Margaritifera---- Rivers of Coromandel - - - 
Corrugata Pravatereneio”, | MELO” See cs cals eitelo eunelels 
Rugosa ----..--- Dyilfos = eae sae vee 
Variabilis ------- South American Rivers: - 
Cc 
Common Name. 
Dutch Gaper -- 
Painters’ -- do -- 
Oval -- «+. do -- 
Radiated -- do -- 
Ponderous- do -- 
Smooth---- do -- 
Knotted --- do - 
Pearl ----- dou 
Wrinkled-- do -- 
Rough ---- do -- 
Variable -- do - 
