DREDGING ON THE COASTS OF SHETLAND. 337 



■wanting in the same part of the sea-bed where I procured the specimens 

 which have given rise to the above remarks. 



Various have been the positions which conchologists have, from time to 

 time, assigned to this remarkable mollusk in their systems of classification. 

 Turton placed it in Pha&lanella ; Fleming in Velutina, biit with doubt ; 

 Eeeve at first between Turritella and Cerithium, but recently between 

 Canalifera and his Turhinacea ; Macgillivray among his Turhinina, and next 

 to Lacuna ; Forbes and Hanley, as well as Woodward, in Fi/ramidellidoi ; 

 H. & A. Adams as a distinct family between Eulimidce and CeritJiiojJsidce ; 

 Clark in Pyramidellidce, between Aclis and Scalaria ; and Gray also in the 

 same family, between his genus Hyala {Rissoa vitrea) and Entoconcha. I 

 am inclined to agree with the Messrs. Adams in making Stilifer the type 

 of a separate family ; but it is much more difficult to say to what other 

 families it has the nearest affinity. Pyramidellidce, as represented in our 

 seas by Odostomia, ought not to be far separated from it ; and lanthinidce 

 have similar relations to it in respect of the nucleus or apex of the sheU. 

 Homcdogyra has sessUe eyes placed on the neck, as in Stilifer, but has no 

 tentacles ; and it is also finely cUiated all over. 



The presence or absence of an operculum is evidently not a character of 

 sufficient value to distinguish one family, or even one genus, from another, 

 seeing that some species of the same genus (e. g. Ifanyelia) possess an oper- 

 culum, while their congeners (although closely allied in aU other respects) 

 have none. 



The stiliform character of the spire in this genus, although remarkable, 

 is not peculiar to it, or to Odostomia, Turbonilla (or Chemnitzia), EidimelJa, 

 or lanthina. Melampus bidlceo'ides has the apical whorls formed in the same 

 mamillated fashion ; and in several genera of Bidlida the shell exhibits the 

 same feature. These, however, may be regarded as cases of analogy rather 

 than of affinity. The nucleus of the spire, or first-formed whorls, in many 

 univalves ceases to be occupied by the animal after it has attained a certain 

 growth, being too small for its requirements — like a householder, who usually 

 moves, once at least during his life, into a tenement larger than the one he 

 at first inhabited. In the case of the MoUusca above referred to, the original 

 and now useless tenement remains fixed to the new one ; but in Bulimus decol- 

 latus, some species of Clausilia, and in TruncateJla truncatida the topmost story 

 is knocked off and replaced by a partition wall. Ccecum glahrum and G. 

 trachea even undergo partial metamorphoses, the shell of each having at first 

 a regular spire, and, when this is lost, becoming a slightly curved cylinder. 

 The genera Leptoconchus of Eiippell and Canvpidotus of Guettard {Magihts, 

 Montfort) also appear to be related to Stilifer in their quasiparasitic habits. 

 The first-named genus is destitute of an operculum, except in its younger 

 state ; the other has an operculum at aU ages (Deshayes, ' MoUusques de I'ile 

 de Reunion'). 



The conjecture of the late Professor d'Orbigny that Stilifer ought to 

 merge in Eidima, and that the latter may be also parasitic, has no founda- 

 tion. It is true that species of Eulima have been found in the stomachs of 

 Holothurite ; and the "trepang," or dried "beehe de mer," of which the 

 Japanese are so fond, frequently contains these shells. But this is not a 

 case of parasitism : the Eulima feeds the Holothuria, instead of feeding 

 upon it. 



Let me say a few words as to the name of this genus and the European 

 species. Although the Greek orthography is followed in our word style, it 

 is clear that the Latin word stilus was not spelt with & y : it is from this 



