RICINtJLA 



in canalem brevem, postice recurvum, oblique 

 emarginatum, terminata. Plicae vel dentes 

 inseqiiales ad columellam et ad internum labii 

 externi parietem, aperturam plerumque coarc- 

 tantes. Operculum corneum, tenue, semilunare. 



That Ricinula is nearly related to Columbella tbere can- 

 not be the smallest doubt ; wherefore^ although Lamarck 

 has placed the one in his Columellaires, and the other in 

 his Purpuriferes, we are convinced they ought to be ar- 

 ranged next to each other, and both in the latter family. 

 Indeed the resemblance is so close, that we think it will 

 prove exceedingly difficult if not impossible to ascertain 

 to which of the two genera some particular species are to 

 be assigned. The RicinulaB, so named from their being 

 muricated externally, resembling the seed vessel of the 

 Ricinus, are mostly small shells with a slender, semilunar, 

 horny operculum. The only character by which we think 

 they can be distinguished from Columbella, is their being 

 covered on the outside with pointed tubercles and spines^ 

 but this is not admitted by Lamarck as a constant cha- 

 racter : two of the shells he describes as Kicinulae having 

 neither spines nor tubercles. In general their spire is 

 short, we believe never so long as the aperture, which is 

 longitudinal, terminated at the base by a short canal 

 turned rather backwards and obliquely notched. There 

 are a few irregular folds or teeth on the base of the 

 Columella, More regular teeth are generally observable 



