fusus. 335 



landicus and F. gracilis (which latter he described as 

 F. Listeri) in the ( Transactions of the Society of Natural 

 Sciences at Hamburg/ The young of the present shell 

 appears to be the F. Sabini of Hancock; Buccinum 

 Sabinii of Gray is another species. Dr. Morch tells me 

 that he regards F. Islandicus as bearing the same re- 

 lation to F. gracilis as F. despectus does to F. antiquus. 

 The Tritonium Islandicum of Loven is F. Berniciensis. 



5. P. gracilis f, Da Costa. 



Buccinum qracile, Da Costa, Br. Conch, p. 124, t. vi. f. 5. F. Islandicus, 

 F. & H. iii. p. 416, pi. ciii. f. 1, 3, and (animal) pi. SS. f. 2. 



Body white, with frequently a tinge of pale yellow : pallial 

 tube short but broad, upturned when the animal crawls : pro- 

 boscis cylindrical, very long* and muscular, fleshcolour on the 

 underside : tentacles triangular and flattened, short, with 

 rounded tips ; they diverge in consequence of being separated 

 by the head-veil, which forms an intervening membrane : eyes 

 small and black, nearly sessile, about halfway up the tentacles, 

 on their outer side : foot oblong, squarish and double-edged in 

 front, with angular corners, expanded at the sides, and bluntly 

 pointed behind. 



Shell broader near the base than towards the other extremity, 

 rather solid, almost opaque, somewhat glossy: sculpture, nume- 

 rous slight spiral ridges, which are defined on the upper whorls 

 by impressed lines ; there are about 16 on the penultimate 

 whorl, 14 on the antepenultimate, 12 on the next, 10 on the 

 next, 8 on the next, and (3 on the next whorl, the upper 

 two whorls being smooth ; the ridges extend to the suture on 

 each side ; lines of growth curved and very fine : colour white 

 (with rarely a tinge of fleshcolour) beneath the epidermis: this 

 is membranous, usually yellowish-brown, lemoncolour, or even 

 of a paler hue in specimens from deep water ; the epidermis 

 is frequently wanting below the periphery, near the upper 

 part of the inner lip, so as to expose a broad triangular patch 

 the base of which is uppermost : spire elongated and abruptly 

 tapering ; apex irregularly mammiform, and twisted in front, 

 but not prominent or forming a bulbous point as in the last 



* Slender. 



