_Young._ Vol. vitulina. _Dill._ 553.--_Martini_ 4. 149. 1380 & 1.
_Variety_ more elongated. Vol. abbatis. _Dill._ 557. _Chemnitz_ 11.
_t._ 177. 1709 & 10.
This (a common sh.e.l.l) can be no other than the _M. ferruginea_ of Lamarck, though neither that author nor any other has noticed its primary distinguishing character, that of the uncommon thickness of the outer lip at the margin, which is also divided into convex obtuse crenations; in young sh.e.l.ls this is not apparent; such is Martini"s figure. Mr. Dillwyn has changed Lamarck"s name to _Vitulina_ for this, and given the name of _Abbatis_ to the variety more lengthened, figured by Chemnitz; but which, from specimens now before us, we consider with Lamarck only as a variety, possessing all the essential characters here given to both.