PEOTUNCULUS. 247 



glossy. In the variety pilosus the sides are generally 

 equal, and the outline only exceptionally oblique : in the 

 more ancient form, the opposite conditions more frequently 

 prevail. In both the ground-colour is whitish or pale red, 

 (in the fry the entire surface, except the colourless beaks 

 and a few small scattered splotches of white, is occasionally 

 rufous,) adorned with more or less broad zigzag markings 

 of dirty red, arranged in the more typical specimens of 

 glycimcris in a large and somewhat radiating pattern, but 

 having a greater tendency in pilosus to cluster together in 

 numerous concentric fillets. The diversity of painting in 

 the younger shells is infinite ; one of the most beautiful 

 of these is the nummarius of Turton (not of Linnams, 

 whose type was a young violascens) which is exquisitely 

 studded all over with minute red dots. Another pretty 

 variation of colouring is where the ground is mottled with 

 white and flesh-colour, and sprinkled with unconnected 

 angular red markings upon the more sparingly distributed 

 patches of the former hue. A white variety has been 

 found at the Arran Isles on the Irish coast by Mr. 

 Barlee. A decussation of most delicate radiating and 

 concentric striulee pervades the exterior, the concentric 

 being the more manifest where the length of the shell 

 exceeds the breadth, the radiating where it is inferior to it. 

 This sculpture is far more prominent in the younger indi- 

 viduals (P. decussatus of Turton), and becomes compara- 

 tively obscure in some of the more aged ones ; in addition 

 there may be seen in certain examples of the variety 

 pilosus a faint appearance (as in Siculus) of obsolete ribs, 

 as though costee had once existed, and been abraded to 

 the level of the general surface. 



The ventral edge is arcuated, and rises nearly equally 

 on both sides, although much more rectilinearly so on that 



