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Show 60 DR. W. BAIRD ON PROTOMA KNOCKERI. [Jail. 2/, As yet, we have only one species; and I propose naming it alter its discoverer. It may be thus defined :- PROTOMA KNOCKERI. Testa elongato-subulata, transversim dense sulcata, sulcis minutis; anfractibus sedecem, plunulatis, suturis distinctis; apertura ovalis, labro infra aperturam acute inciso; operculum circu-lare, parvum, multispirale, corneum. Long. 2\ poll. Hab. Whydah, west coast of Africa (Capt. H. H. Knocker, R.N.). This species resembles in some respects, generically, the Proto cathedralis oi Defrance. It is much smaller than that shell, however ; the sulci or ridges are much finer and more numerous; and there are no large circular ribs or sulci at the base of the last whorl. Instead of merely an emargination on the under lip, this part of the shell is more sharply cut or incised, and the slit is more profound. The operculum, which fortunately exists in one specimen, is small, circular, and resembles that of Mesalia or Turritella. It is difficult to say what the colour is, as in the largest specimen we possess the shell is brown, while in all the others it is quite white or colourless. Remarks on the Genus Proto of Defrance. Taking the Turritella cathedralis of Brongniart to be the type, as Deshayes (in the last edition of Lamarck's 'An. sans Verteb.') asserts it to be, of the genus Proto of Defrance, I was at first induced to consider the shell just described a species of that genus. A further examination, however, has decided m e to alter m y opinion, as the following observations will show. In 1815, in the eleventh volume of the 'Linnean Transactions,' Leach established the genus Proto for a particular species of amphi-podous Crustacea. This name has since then been adopted by Desmarest (in 1825), Johnston, A. White (in his * Catalogue of the Crustacea in the British Museum'), and by Spence Bate (in his ' Catalogue of the Amphipoda in the British Museum'). In the same year (1815) the name oi Proto was given by Oken, in his ' Lehrbuch,' to a genus of Annelidan worms belonging to the Naiadina. This genus was subsequently adopted by ffirsted in Kroyer's 'Tidsskrift' in 1843, and by Johnston in his 'Catalogue of the Non-parasitical Worms in the British Museum.' Grube, however, considers the genus Proto to be synonymous with another genus established by Oken in the same work, and called by him Dero. If this synonymy be correct and the genus Dero be adopted, we shall then have no difficulty in giving precedence to the genus formed by Leach. To render the word Proto, however, still more perplexing, Defrance gave the same name to a genus of shells. In the ' Diet, des Sc. Nat. vol. xliii. (published in 1825), this author defined his genus ; and about the same time it made its appearance in De Blainville's ' Manuel de Malacologie.' As the species upon which Defrance founded his genus was figured by him (and reproduced by Blainville in the |
