TELLINA. 305 



Although the name soUdula is well established, the 

 specific appellation ruh-a was previously bestowed upon 

 this shell by Da Costa, an epithet which we wish not to 

 resuscitate, since not only is it peculiarly unsuited to a shell 

 with so variable a colouring, but emanates likewise from an 

 author who, having wilfully passed over the just claims of 

 his predecessors in nomenclature, has forfeited the right of 

 challenging for himself the law of priority. It is by no 

 means certain after all, that this bivalve is si)ecifically dis- 

 tinct from the Baltliica of Linnaeus ; the diiferences at 

 least, although sufficiently definite, not being greater than 

 what are avowedly induced in other species by the peculiar 

 nature of the waters of the Baltic sea, under whose influ- 

 ence the majority of the marine shells become depau- 

 perated. 



The form is rounded, ovate, and longer than broad 

 (more rarely suborbicular) ; the valves are equilateral, 

 opaque, strong, and more or less ventricose, the convexity 

 being most marked near the umbonal region, diminishing 

 below it, and more especially lessening towards the pointed 

 extremity. The surface, except in aged examples, is more 

 or less glossy, and both externally and internally of the 

 same hue, although the interior is frequently of a deeper 

 tone. The colouring matter is often disposed in darker 

 and paler zones, and never in rays or spots ; it is infinite in 

 diversity, various shades of yellow, flesh, orange, and pink, 

 occupying the entire surface ; the valves more rarely are 

 almost white. There are neither strife nor sulci, but only 

 a few antiquated lines of growth. The ventral margin is 

 well arcuated in front, but becomes straighter and some- 

 what ascending behind, where it forms an acute angle be- 

 low with the much declining and scarcely convex dorsal 

 edge. 



VOL. I. R K 



