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Genus 10. FUSUS, Lamarck. 



Animal ; disk somewhat square and comparatively small, usually 



furnished with a, horny operculum acuminated towards the 



head; head very small, ivith tioo tentacles of moderate length 



in which the eyes are placed, sometimes at the base, sometimes 



toioards the middle. 



Shell ; ovately or elongately fusiform, nerves varicose, canalicu- 

 lated at the base, canal sometimes very short ; columella smooth ; 

 lip of the aperture generally denticulated. 



It is a feature in the canaliferous tribe of mollusks that a much greater 

 variety of character for the formation of genera is presented in the shell 

 than in the animal, and the same may be observed in regard to species. 

 The soft parts of Fusus differ in no material degree from those of Murex, 

 Triton, or Fleurotoma, the disk, head, and tentacles having the same general 

 proportions, whilst the operculum of each is acuminated anteriorly in like 

 manner ; and in the present genus, though one species may have a long 

 turriculated shell, as in the F. longissimus, and another an ovate abbreviated 

 shell, like that of F. despecim, there is no particular variation in the animal 

 except in regard to bulk.* 



The genus Fusus has, on this account, been considered of somewhat 

 doubtful importance ; the knowledge of this similitude in the animal has 

 even elicited a sort of negative argument in favour of its abandonment, 

 that might be applied with equal force to any group in the series. 

 " Take away the columellar plaits from the greater portion of the Turbinetla," 

 says M. Deshayes in the work quoted below, " and you make Fusi of them ; 

 deprive the Tritons of their varices, and they become Fusi " it must, how- 

 ever, be remembered, that the genera of this class, though systematic;) liy 

 characterised by the presence or arrangement of the columellar plaits, are 

 further distinguished, each by a distinct association of peculiarities. It needs 

 no examination of the varices to distinguish a Murex from a Triton, or 

 Ranetta, and still less of the columellar plaits, to discriminate between 

 the solid tuberculated Turlriietlus and the comparatively delicately nodulous 

 Fusus. The typical difference in the shells of Turbmellus and Fusus, apart 

 from any consideration of the soft parts, must strike every observer ; and it 



* M. Deshayes inclines to think, from observations he lias had an opportunity of making on 

 the living Fusus, that there is a difference in the position of the eyes corresponding to these 

 divisions. " If the animals of a larger number of species were known," says that acute observer, 

 "it is probable that the situation of the eyes would afford a character for the distinction of two 

 natural groups, for it may be remarked that in those species which have a narrow elongated 

 canal the eyes are at the base of the tentacles, but in the ovate short-canal species they arc 

 upon the middle." — Anim. sans. vert. vol. ix. p. 442. 



