Having seen but a single specimen of this shell, I have placed it as a distinct species, not without some doubts, and principally for the purpose of calling the attention of conchologists to a more rigid examination of the specific distinctions of this family (unconnected with colour) than has heretofore been done. The regular convexity of the whorls, not in any degree compressed at the suture, the want of that thickened appearance on the spire, and of the contraction at the base of the mouth (all which characters I have found in the varieties of _B. citrinus_ to be constant), afford a specific distinction which future observations must confirm or annul. Bruguiere notices a variety of _B. citrinus_ which is entirely yellow, a most beautiful specimen of which is in the British Museum, and which possesses (as well as the excellent figure of Gualtieri) all the specific characters I have given to _B. citrinus_, but not of the present shell. Lister's figure, on the contrary, is rude, though very characteristic of this; and Martini's representation, here cited, also appears the same. Mr. Dubois, in whose collection this specimen exists, is unacquainted with its locality. * * * * * Pl. 48 [Illustration] MITRA casta, _Chesnut-banded Mitre._ * * * * * GENERIC CHARACTER.--See Pl. 23. * * * * * SPECIFIC CHARACTER. _Mitra (Div. 3.) testa alba, laevi, olivaeformi, spira apertura breviore, anfractibus supra tenuiter reticulatis, basi epidermide castaneam fasciam formante, in anfractu basali centralem et latam._ Shell white, smooth, olive-formed, spire shorter than the aperture, the volutions finely reticulated above, the lower half with the epidermis forming a chesnut band which is central and broad on the basal whorl. Voluta casta. _Chemnitz_ 10, _p._ 138, _vig._ 20 C D.--_figura mala_. _Martyn Univ. Conch._ i. _tab._ 20. _Dillwyn Catalogue_, _vol._ i. _p._ 554, _no._ 127. * * * * *