62 MOLLUSCA FROM THE GREAT OOLITE. 
7. Testdé turbinatd; spird elatd; anfractibus (5) subconvewis, longitudinaliter costatis; 
costis 12 rectis elatis; basi levi; apertura parvd, depressda. 
Shell turbinated; spire elevated; whorls (5) rather convex, longitudinally costated ; 
coste straight, elevated, smooth, about 12 in a volution; the base smooth; the aperture 
small and depressed; the sutures of the whorls are strongly marked. Axis 3 lines, basal 
diameter 6 lines. 
Locality. The specimen figured is rather flattened; it occurred in the planking of 
Minchinhampton Common, and is more acutely conical than that figured by M. d’Archiac, 
of which it is considered to be only a variety. 
Trocuus Ipprtsont. Plate X, figs. 4, 4a. 
T. Testé conicd, spirdé elatd, obtusd; anfractibus (5—6), levigatis et planis, aut sub- 
convexis; apertura depressd, obliqua; umbilico nullo. 
Shell conical; spire elevated, obtuse; whorls (5—6) smooth and flattened, or slightly 
convex ; aperture depressed, oblique; no umbilicus, columella lip thick and excavated. 
This species somewhat resembles 7. Dunkeri, from which it differs in the more elevated 
spire, obtuse apex, and somewhat convex form of the whorls; the base is, likewise, more 
convex and narrow: in the larger specimens these distinctive characters become more 
prominent, and the sutures of the whorls are strongly marked. It occurs together with 
T. Dunkeri, but in smaller numbers. 
Locality. Hastscombs and Bussage. 
The name in compliment to Capt. L. L. B. Ibbetson, F.R.S., whose geological surveys 
of the different railways have been of considerable interest to science. 
Trocnus squamicER. Plate X, figs. 2, 2a, 6. 
T. Testé conicd; apice obtuso; anfractibus (6—8) subcompressis, suturis impressis; 
anfractibus cingulis quaternis tubuloso-squamosis; cingulo inferiort minimo; basi pland et 
levi; aperturd depresssd; umbilico nullo. 
Shell conical; apex obtuse ; whorls (6) rather compressed, the sutures well marked ; 
whorls with four circles of nodules or plications which are squamosely tubular or excavated 
towards the aperture, the lowest circle of nodules being much the smallest ; the base is flat 
and smooth; the aperture depressed ; no umbilicus. 
In this species the height exceeds the basal diameter. It occurs not very unfrequently 
in the planking, a rock which usually adheres very closely to shells, and the plications 
become entangled with the particles of stone, so as to render good specimens very rare. 
Locality. Minchinhampton. 
