208 MYTILID^. 



C. RHOMDEA, Berkeley. 



Very small, somewhat rhomboidal, wliitish ; entire surface 

 sculptured with radiating lines. 



Plate XLV. fig. 3. 



Afodiola Prideauxiana, Leach, Zoolog. Miscellany, vol. ii. p. 35. — Brown, IU. 

 Conch., G. B. p. 78, pi. 27, f. 9. 

 „ rliowLea, Berkeley, Zoolog. Journal, vol. iii. p. 229, suppl. pi. 18, f. 1 

 — Brit. Marine Conch, p. 107. — Brown, 111. Conch. G. B. 

 p. 78, pi. 39, f. 17. 



Although this extremely rare shell had previously been 

 observed by Dr. Leach, yet as his brief description, unac- 

 companied by a figure, is so entirely inadequate for its re- 

 cognition, that, without a knowledge of the typical example, 

 it would have been impossible to ascertain what was intended 

 by it, we have preferred the name subsequently assigned to it 

 by Mr. Berkeley. It is a remarkable-looking species, and 

 incurs not the slightest risk of being mistaken for any other 

 British shell, but bears, when worn, a close resemblance to 

 the young of C. sulcata. The shape is rather oblique, 

 somewhat rhomboidal, and occasionally a little arcuated ; 

 the chief dilation is a little beyond the middle, the hinder 

 termination being distinctly attenuated. The valves, which 

 are white, covered when recent with a pale yellow epi- 

 dermis, are much swollen, or gibbous, above upon the um- 

 bonal fold, but are compressed near the dorsal angle, and 

 rather quickly diminish in convexity towards the ventral 

 margin. Their texture is rather strong for their size, and 

 neither transparent nor vitreous ; the exterior is not polished, 

 though a little glossy, and is most exquisitely sculptured by 

 radiating lines, which are delicate and most closely set 

 in front, but elevated, more distant, a little divergent, and 

 often bifurcated posteriorly. In the perfect state these are 



