PIRENA.— Plate II. 



Species 11. (Mus. Cuming.) 



Pikena plicata. Pir. testa oblotigo-turriculatd, j'erru- 

 gineo-brunned, anfractibus quinqiie, deinde decollate, 

 striis elevatis undique dense funiculatis, longitudina- 

 liter plicato-costatis, anfractiis ultimi costis obsoletis ,■ 

 apertnra rotundatd, mediocriter sinuatd. 



The plaited Pirena. Shell oblong-turriculated, rust- 

 brown, whorls five, then decollated, densely corded 

 throughout with raised striae, longitudinally plicately 

 ribbed, ribs of the last whorl obsolete ; aperture 

 rounded, moderately sinuated. 



Hab. West Africa. 



The last three species pass gradually into each other, but 

 taken separately they are very distinct. P. spinosa is a light 

 subinfiated shell, smooth and shining, with very prominent 

 prickly tubercles. In P. Jluminea the shell is less inflated, 

 the prickly tubercles resolve into numerous prickly ridges, 

 and the shell is corded throughout with raised stria;. In 

 P. plicata the shell is a compact solid mass, still corded 

 throughout with raised striae, but having in the place of 

 prickly edges a series of concentric ribs devoid of prickles, 

 and the sinuated clefts of the aperture are only feebly de- 

 veloped. 



