BIVALVES. — DON AX. 



Family 2. — Having a striated or wrinkled surface. 

 Stiiatula — Substriaied. Nitida — Delicate. 



Plicataria — Plaited. Striata — Striated. 



Papyracea — Paper. *Radiata — Rayed. 



Vitrea — Brittle. *^o\\AdL— Strong. 



Cygnea — Swan. Solidissinia — Thick. 



Turgida — Inflated. *Truncata — Truncated. 



Violacea — Violet. *Subtruncata — Abrupt. 



Cuneata — JVedge-shaped. Australis — Southern. 



Rotundata — Roundish. Piperata — Pepper. 



Glahrs^tSL— Smooth. *Tenu\s— Thin. 



*Boysii — Boys'. 



Division II. — Shell ovate, obloxg. 



FaiSIILY I. — Closed at both ends. 

 *Glauca — Red-rayed. Riigosa — Rugged. 



Egyptiaca — Egyptian. 



Family 2. — Gaping at the anterior end. 

 Pellucida — Pellucid. *Fragilis — 'Brittle. 



*Listeri — Lister's. 



Family 3. — Gaping at both ends, 

 ^rianeitd,— Flattened, »Lutraria — Muddy. 



* H ians — Gaping. 



DONAX. — Wedge-shell. 



Animal — a Tethys: Shell hivalce, ivilh generally a crcnu- 

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

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

 hind, rarely double or trijyle. 



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, heing very broad and thick at 

 one extremity, and gradually narroAving and lessening to 



