Fusus. 417 



JFusiis Islandicus of Chemnitz as a distinct species ; we 

 believe, however, that MiddendorfF, who has laboriously 

 investigated the laws that regulate the extent of varietal 

 distinctions, has correctly reunited the two forms. 



Beneath a glossy and smoothly attached conspicuous 

 epidermis, that is yellow, or brownish yellow on the pale 

 examples, and brown on the darker ones, this graceful shell, 

 which is fusiform or oblong-fusiform in figure, is of an 

 uniform tint, that ranges from pure white to pale vinous 

 red, or ochraceous flesh-colour. It is adorned with frequent 

 and very depressed spiral costellse, which are generally, but 

 not always, so closely disposed on the earlier turns, that the 

 volutions should rather be termed sulcated, but on the final 

 whorls are inferior in breadth to the intervals between 

 them : there are some faint and minute longitudinal 

 wrinkles, but no regular series of them, as in the larger 

 allied species. Of the eight volutions that compose the 

 shell, the apical coil in the typical forms is usually dis- 

 torted, mammillary, and larger than the succeeding one ; 

 the rest are of moderate longitudinal increase, are convex 

 or subventricose (sometimes even rounded), taper gradually 

 above, and are peculiarly well defined, not merely by a 

 profound sutural line, but by the almost perpendicular 

 abruptness with which they rise from it ; sometimes they 

 convexly shelve above to the suture ; sometimes they sub- 

 angulately project there beyond each other : the latter is 

 usually the case in those examples, in which the blunt- 

 pointed spire, which is always gradual in its attenuation, 

 is shorter than usual. The body slightly exceeds the rest 

 of the whorls united, and usually occupies five-ninths of 

 the total length, it tapers below i-ather suddenly, and very 

 considerably, to a more or less curved and somewhat 

 twisted, but neither slender nor much produced tail, so 



VOL. III. 3 H 



