APPENDIX. 319 
Rissoa THERMALIS? Linneus. Tab. XXXI, fig. 12, a, 4. 
TURBO THERMALIS. Linn. Syst. Nat., 12th ed., p. 1237, No. 629. 
— Muriaricus? Beudant. Ann. du Mus., tom. xv, p. 201. 
Spec. Char. “T. umbilicatd oblongiusculd, obtusd, anfractibus teretibus levibus.’—Linnzus. 
Shell elongately conical or subulate, naked, smooth, and glossy; volutions six, slightly convex; 
suture distinct and deep; apex obtuse, depressed; aperture ovate; inner lip adpressed, giving a pointed 
termination at the upper part; umbilicus small. 
Length, inch. Diameter, § of the length. 
Locality. Clacton. 
It is now most difficult, perhaps impossible, to say what Linnzeus intended for the type of his Turbo 
Thermalis, as there are two or three species that might, with a moderate allowance of latitude in variation, 
be made to accord with the diagnosis of his shell, and, it is to be feared, have already been done so. I am 
unwilling to make ‘confusion worse confounded,” so have introduced our shell with the above name 
instead of imposing a new one, though not without great misgivings upon the propriety of doing so, 
particularly as Linnzeus, in his description, says, ‘'T. semine Brassicee paulo major.” 
Our fossil is by no means rare at Clacton, but the majority of my specimens were obtained from the 
clay or estuary portion of the deposit at that locality in association with marine or rather estuary species: 
Cardium edule, Tellina Balthica, Trigonella plana, Mytilus edulis, and Balanus. I have also found 
specimens in the sandy and purely fresh-water part of the cliff, with land and fresh-water shells, so that 
probably its animal inhabitant was capable of residing in water that was either fresh or brackish. Mr. 
John Pickering has presented me with some specimens of a recent shell identical with our fossil, and these, 
he tells me, were obtained in the ditches of brackish water near Gravesend, in Kent. Similar specimens 
were pronounced by Messrs. Forbes and Hanley, vol. iv, p. 267, to be only varieties of &. ventrosa, in which 
opinion I cannot coincide ; and I am permitted by Mr. Pickering to say he believes the two shells to be 
specifically distinct. 
This shell, or something very like it, was found by MM. Ehrenberg and Von Hemprich, “in fontibus 
Oasis Jovis Hammonis inter Alexandriam et Rosettam.” 
JEFFREYsIA? paruLa, S. Wood. Tab. XXXI, fig. 14, a, 6. 
Narvica DEPRESSULA. S. Wood. Catal. of Crag Shells, Ann. and Mag. Nat. Hist., 1840, 
p. 930. 
Spec. Char. Testd minutd, subglobosd, levigatd, politd, tenui, vitred, pellucidd? umbilicaté ; apice 
obtuso ; anfractibus paucis 1\—2 depressis ; suturis profundis, excavatis ; aperturd magnd, ovatd, dilatatd ; 
labro simplici acuto. 
Shell small, subglobose, smooth, glossy, thin, vitreous, pellucid? umbilicated; apex obtuse; volutions 
few, 1—2, depressed; suture deeply excavated; aperture large, ovate, expanded; outer lip thin and 
sharp. 
Diameter, +'; inch. 
Locality. Cor. Crag, Sutton. 
Three specimens of a small species were found by myself many years since, and reserved to the present 
time. They are now assigned provisionally to the above genus, more from the difficulty of finding a better 
position than from a satisfaction of their correct appropriation. ‘They appear to differ from Natica, where 
