BIVALVES. DONAX. 47 



FAMILY 2. Having a striated or wrinkled surface. 

 Striatula Substriated. Nitida Delicate. 



Plicataria Plaited. Striata Striated. 



Papyracea Paper. *Radiata Rayed. 



Vitrea Brittle. *Solida Strong. 



Cygnea Swan. Solidissima Thick. 



Turgida Inflated. *Truncata Truncated. 



Violacea Violet. *Subtruncata Abrupt. 



Cuneata - Wedge-shaped. Australia Southern. 



Rotundata Roundish. Piperata Pepper. 



Glabrata Smooth. *Tenuis Thin. 



*Boysii Boys'. 



DIVISION II. SHELL OVATE, OBLONG. 



FAMILY 1. Closed at both ends. 

 *Glauca Red-rayed. Rugosa Rugged. 



Egyptiaca Egyptian. 



FAMILY 2. Gaping at the anterior end. 

 Pellucida Pellucid. *Fragilis Brittle. 



*Listeri Lister's. 



FAMILY 3. Gaping at both ends. 

 * Pianata Flattened. *Lutraria Muddy. 



*Hians Gaping. 



DONAX. WEDGE-SHELL. 



Animal a Tethys: Shell bivalve, with generally a crenit- 

 late margin, the frontal margin is very obtuse; hinge with 

 two teeth, and a single marginal one placed a little be- 

 hind, rarely double or triple. 



THE most leading characteristic of the Donax is deriv- 

 ed from its form, which (throughout the twenty-four-species) 

 is similar to that of a wedge, being very broad and thick at 

 one extremity, and gradually narrowing and lessening to 



