396 TELLINID^. 



3. P. Ferroensis *j Chemnitz. 



Tettina Ferroensis, Chemn. Conch. Cab. vi. p. 99, 1. 10. f. 91. P. Ferro- 

 eizsis. F. & H. i. p. 274, pi. xix. f. 3. 



Body elongated, white or of the palest brown : mantle clothed 

 with a short white fringe, or rather with fine dentations : tubes 

 of nearly equal size and length ; the branchial is somewhat 

 the larger and longer, and when not fully extended it appears 

 finely corrugated and marked with two longitudinal bars, and 

 its orifice has six plain cirri; the excretal tube curves up- 

 wards, and its orifice has no cirri : gills and palps nearly as 

 in P. tellinella : foot very large, flat, long, and bevelled to a 

 sharp edge. 



Shell oblong and somewhat rhomboidal, compressed, rather 

 solid, opaque, more or less glossy when not covered by the 

 epidermis ; the right valve is usually larger than the other and 

 slightly overlaps it : sculpture, numerous fine, but not raised, 

 concentric ridges, which are sharper on the anterior side and 

 often laminar or slightly imbricated on the posterior side, be- 

 sides minute and close-set parallel stria? in the interstices of 

 the ridges ; the surface is also covered with slight and indis- 

 tinct longitudinal or radiating lines, and the posterior slope or 

 area is often more or less marked with half a dozen slight 

 ribs, which radiate from the beaks and (especially in the 

 young) produce a cancellated and prickly appearance by their 

 intersecting the transverse ridges : colour beneath the epider- 

 mis pink of different shades, diversified by longitudinal rays 

 of yellow or milk-white, some of which are broader than the 

 rest and frequently confluent or broken ; the surface also is 

 often marbled with short white lines or streaks ; now and then 

 (but rarely) the colour is uniform purple : epidermis thick, 

 fibrous, more persistent than in either of the preceding species, 

 dusky in the adult and yellowish with a green tint in the 

 half-grown and young : margins not much rounded in front, 

 and occasionally almost straight, semioval, and wedge -like on 

 the anterior side, abruptly and obliquely truncate on the pos- 

 terior side, with an indentation or flexure on the ventral side 

 of the posterior angle ; a keel extends from the beak to this 

 angle, and the area thus separated is flat or depressed, and 

 sculptured by the radiating ribs above mentioned ; the dorsal 

 or ligamental margin is serrated in specimens strongly sculp- 



* Belonging to the Faroe Isles. 



