GASTEROPODA. A] 
Ihave given the name assimélis from its close similarity, in all other respects than size, 
to the large Bridlington shell rodvsta. The uniformity in size between the Crag specimen 
and the two Middle Glacial ones, renders it probable that the specimen figured is full 
grown ; I have, therefore, considered this species as distinct from rodusta, and assigned 
to it a separate name. It is, however, possible that, as some existing shells assume 
gigantic proportions under certain arctic conditions, the shell thus appearing in the Red 
Crag before the Glacial conditions had actually fallen upon Britain, and occurring in 
similar size in the Middle Glacial Sand by virtue of those causes, whatever they may be, 
to which the presence of so many southern species in these sands is due, became inflated 
by the truly arctic conditions under which the Bridlington shells lived, to the gigantic 
dimensions possessed by the species I have figured under the name of rodusta, The shell 
differs from Trevelyana in the greater length of the body whorl relatively to the spire, 
and in having a less prominence of shoulder: also in its greater size. 
PirvROTOMA HyYSTRIX, Jaz. Supplement, Tab. VI, fig. 3, a, 6. 
PLEUROTOMA HISTRIX, Jan. Catal., p. 10, No. 59, 1832, fide Bellardi. 
RHAPHITOMA HISTRIX, Bellardi. Mon. delle Pleur. Foss., p. 85, t. iv, fig. 14, 1847. 
DeEFRANCIA HIsTRIx, 4. Bell. Ann. and Mag. Nat. Hist., September, 1870. 
Spec. Char. “ Testa subfusiformi, elongatd, angusta, costis longitudinalibus et trans- 
versalibus exilissimis, lamellosis clathrata; in earum intersecatione papulis acutis, erectis 
hirsuta; anfractibus planiusculis, elongatis, posticé levibus ; spira elata, apertura ovato- 
elongata ; labro intus sulcato ; canali longinsculo.’’—Bellardi. 
Length, +-sths of an inch. 
Locahties. Cor. Crag, Sutton (Bell). Red Crag, Walton-on-the-Naze. 
The specimen figured was obtained by myself from Walton, from which place another 
has since been obtained by Mr. Bell. It much resembles Fusus cancellatus, J. Sow., 
Clavatula cancellata, ‘Crag Moll.,’ but the present shell is more elongated, and there is a 
broad sinus adjoining the suture ; this leaves a blank or naked depressed space at the top 
of the volution, or at least shows only lines of growth of the sinuated aperture. The 
shell is elegantly cancellated, and the outer lip is somewhat thickened and denticulated on 
the mside. This is not Murex hystriz, Linn. Mr. Bell gives the species as from the Cor. 
Crag. (Ann. and Mag. Nat. Hist.,’ May, 1871), but I have not seen the specimen. 
PLEUROTOMA TENUISTRIATA, 4. Bell, Crag Moll., vol. i, p. 62, Tab. VII, fig. 12 (as 
Clavatula levigata). 
PLEUROTOMA TENUISTRIATA, A. Bell Ann. and Mag. Nat. Hist. for May, 1871. 
Locality. As in ‘ Crag Moll.’ 
6 
