38 BIVALVES—— DONAX. 
ed strize, crossing each other in a transverse and longi- 
tudinal direction, thus giving the shell a spiny appear- 
ance, as in the D. scortum and D. pubescens. The 
second and third divisions are also characterized by the 
position of the strice, which in the one are longitudinal, 
and in the other transverse. The shells of the fourth 
division have a smooth and polished surface; and the 
fifth at present consists of one species only, which has 
its surface partially covered with transverse membrana- 
ceous ridges. | 
The most prevailing color is a rich purple, which 
sometimes only appears in rays on a white ground, di- 
verging from the beaks to the margin. Many of the 
species are of an olive-yellow tinge, which often in- 
clines to a bright orange; and others, again, have a 
pink hue, finely diversified with brown zigzag mark- 
ings, as in the D. scripta, &c. and in some instances the 
shells are variously banded. The interior almost al- 
ways partakes of the coloring of the exterior. 
{t is doubtful whether any shells of this genus are 
natives of rivers, as they are generally found buried 
in the sand of the sea shore. Although the species 
and varieties are but few, and thinly scattered over 
most parts of the globe, yet some coasts (the European 
in particular) supply a profusion, but of no great 
variety. 
The Donax derives its name from its shape, which 
resembles the barbed head of a javelin or dart (Sovaé). 
