GASTEROPODA. 3 



a British shell." This undulation is produced by a sinuated form of the outer lip, and 

 is probably a distortion, and if so the specimens are not likely to be very numerous. 



Trophon muricatus, Mont. Crag Moll., vol. i, p. 50, and 1st Sup., p. 28. 



Trophon muricatus var. exossus. 3rd Supplement, tab. i, fig. 3, 1882. 



Locality. Red Crag, Felixstowe. 



The specimen figured as above was recently found by me, and though in excellent 

 preservation is quite destitute of the longitudinal ribs present in the ordinary form of this 

 species. I have therefore distinguished it as a variety, under the name of exossus. 



Pleurotoma turris, Lamarck, 3rd Sup., Tab. I, fig. 8. 



Pleurotoma turris, Lam. An. sans Vert., torn, vii, p. 97, 1822. 



— — — Ibid., 2nd ed., torn, ix, p. 367, 1843. 



— — — Ency. Method., p. 795, t. 441, fig. 7, 1832. 



— — Nyst. Coq. foss. de Belg., p. 525, 1843. 



Murex interruptus, Brocchi. Conch, foss. Subap., p, 433, pi. ix, fig. 21, 1814. 



Spec. Char. "T. fusiformi-turrita, transversim sulcato-rugosa ; striis longitudinalibus 

 tenuissimis in areis planulatis per undulatis ; anfractibus, infra medium ungulatis, ultra 

 angidum plano-concavis, prope suturas marginatisJ' 



Axis, \\ inch. 



Locality. Red Crag, Felixstowe. 



There is some confusion respecting the name of this species. Lamarck described 

 two species as interruptus, one a recent and very distinct shell, the other a fossil for which 

 he adopted the specific name of {Murex) interruptus, referring it to the Murex interruptus 

 figured and described by Brocchi in 1814 ; but a shell named Murex interruptus had. 

 been described by Pilkington in ' Trans. Linn. Soc.,' for 1804, vol. vii, T. 11, f. 5 (and 

 also figured in * Min. Conch.,' T. 304), which takes precedence and is entitled to that 

 specific name. I have therefore adopted the above specific name of turris for the fossil 

 from the Red Crag, Pilkington's species being a British Lower Tertiary form, and quite 

 distinct from our present shell which is a Bolderberg and Italian species. 



Bellardi has represented two shells under the name of Pleurotoma interrupta, 

 considering them only as varieties of the same species, and the specimen from the Red 

 Crag at Waldringfield, figured in my first Supplement, T. V., f. 1, seems to corres- 



