BIVALVES. 



PLATE LVIII. 



Genus. DON AX. 



Character. Shell having the front margin very much thickened ; the hinge hav- 

 ing two teeth, also a marginal one standing under the posterior opening. 



Species. 



No. 1. Donax variegata. Shell angular, slightly laminated, marked, trans- 

 versely, with bars of a blue colour, upon a light yellow ground. This shell 

 is supposed to be very rare, and is delineated from a specimen in the British 

 Museum, amongst those presented to it by Mr. Cracherode. 



No. 2. Donax crenata. Shell of a pale yellow, with a reddish edge in the front, 

 furrowed all over with narrow ridges, the general form triangular. Native 

 place unknown. 



No. 3. Donax sulcata. Shell white, having transverse bars of red ; the hinge 

 end much incurvated, or bent upwards. From a shell in the Author's 

 Museum. 



Genus. VENUS. 

 Character. Shell, the front lips projecting, three teeth, approximate, diverging. 

 No. 1. Venus furbellata. Shell of a pale pink colour, having five deep ridges 

 near the outer edge, slightly undulated. Found in the South Seas, and 

 New Holland. 

 No 2. Venus radiata. Shell of a pale red colour, having seven or more ridges 

 furbelowed and sinuated, armed at the edge with twisted spines projecting 

 like horns. This curious shell is a native of New Zealand. 

 No. 3. Venus disjecta. Shell of a pale red, and ramified. 



REMARKS. 



The genera Donax and Venus bear a very considerable resemblance to each other in their 

 external form, having a deep notch or indentation placed close under the hinge. The dif- 

 ference of the teeth, however, and their internal arrangement, is found sufficient, according 

 to the classical arrangement of Linnaeus, to separate them completely. 



The present arrangement of the Bivalve shells upon the principles of that great Writer, de- 

 pending much upon the internal structure of the hinge, may perhaps in future make it neces- 

 sary to enlarge very much the number of these genera, as new species are almost daily 

 discovered and brought from the southern regions of the globe, which differ in the character 

 or number of the teeth from all those at present known. For the present, therefore, we 

 have adopted the Linnsean arrangement, omitting the genus Mactra, of later Writers, which 

 we conceive requires farther investigation, and which would lead to particulars not connected 

 with the plan of the present Work, which, in respect to the Bivalves, must necessarily be 

 much abridged and concise in its definitions. 



