CONCHYLIA— D/THri?^. 1. 



Wood, Conch, p. 81. tab. 15, fig. 3 to 5. 



Dillwyn, Descript. Catal. p. 40. 



Turton, Conch. Diet. p. 146. 

 Pholas bifrons. Dj, Costa, Brit. Conch, p. 213, tab. 16, fig. 4. 

 Pholas latus. Lister, Conch, tab, 436. fig. 279, and Append. 



tab. 19, fig, 3. 

 Mus. nost. In rocks and hard clay. 



Shell usually an inch and a half long, and two in breadth, whitish 

 or ferruginous, much thicker and stronger than the other species, 

 rounded at the hinder end and produced into a short beak at the 

 other : from the middle of the hinge runs a longitudinal groove, 

 dividing the valves into two nearly equal portions, the anterior or 

 more produced portion marked with strong transverse muricate striae 

 on the outer surface, the other part marked with plain and rather 

 obscure ones : hinge smooth, and without any elevated process on 

 the margin above the teeth. In consequence of the length being 

 nearly equal to the breadth, the valves have a somewhat triangular 

 appearance, causing both the extremities to be very open. 



Lister, in his appendix ad Hist. Anim. Angl. p. 44, observes, 

 that there is a small accessorial valve at the hinge :"huic quod 

 imprimis notandum est, etiam tertia testa exigua est ad valvarum car- 

 dinem." And Linne Mus. Keg. Lud. Ulr. p. 469, makes the same 

 remark, taking Lister for his authority: "accessoria tertia ad cardi- 

 nem exigua. Lister, hujus ideoqui generis." We have not as yet been 

 fortunate enough to find it in its native lodgement. 



