DONAX. 311 



brevi, alta, obtuse angulata, purpurea sen pallide violacea, antice 

 laevigata, rotundatini acuminata, postice lata, tenuiter striata, 

 niargiue ventrali medio subconvexo, angulo postico obtuso, area 

 postangulari convexo, medio obscure angulato, prope umbones 

 complanato. — Although the variety of this well-known species, 

 named I), epidermia, is generally rather longer and less elevated 

 in form than the dark purple one, there can be no doubt that it 

 is identical. 



38. Ticaonicus (f. 96), Hani. — Testa trigono-elevata, tenui- 

 uscula, pallide purpurasceuti, postice obtuse angulata, rugata, 

 antice attenuate, subacumniata, latere antico-dorsali incurvo, um- 

 bonibus acuminatim producto-subrotundatis. — Eemarkable for the 

 acuminately produced umboues, and the incurved character of the 

 anterior dorsal slope. 



39. cuneatus (f. 88, 89, 90), Linn. — Testa obtuse trigona, 

 compressa, laevigata, alta, alba vel fusco-nigricanti vel carneo- 

 fulva, postice obtuse angulata, post angulum undulatim granoso- 

 rugata, margiue ventrali intus laevigata. — A broad compressed 

 shell, distinguished by undulating, granulated rugosities on the 

 area behind the angle. D. grauosa is most probably a variety of 

 this. 



40. comphessus (f. 97), Lamk. — Testa D. cuneata simillima, 

 sed magis elevata, umbonibus productis, margiue antico-dorsali 

 subincurvo. — The greater depth from apex to ventral margin and 

 the concave outline of the antero-dorsal slope distinguish this 

 from U. cuneata. 



41. columellus (f. 113, 114, 115). — Testa quain B. cuneata 

 magis ovali, angulo postico magis rotundato, rugis postangularibus 

 tenuissimis. — More oval than I), cuneata, with the posterior side 

 more rounded and much more finely ridge-striated. 



42. BicoLOit (f. 102, 103), Lamk. — Testa ovali-subcuueata, 

 compressa, antice et medio lrevi, postice granulation striata, alba, 

 late fusco-grisescente fasciata, vel grisea, obscure fusco radiata, 

 postice obtuse biangulata, margiue ventrali convexa, intus laevi- 

 gata, area postangulari concava. — The posterior side of this shell 

 has a very obtuse angle in the usual part, and a second angle in 

 the middle of the area; the area is grauosely striated. 



43. incarnate (f. 98, 99), Chenin. — Testa brevi, compressa, 

 elevata, earned seu alba, purpurco ad umbones radiata, antice 

 hevissima, subacuminata, postice rectiuscula, ante ct post angulum 

 striis radiautibus et ruins subconcentricis undulatis decussata : 



