127 
TROCHUS concavus. 
TAB. CCLXXIT.— Fig. 1. 
Spec. Cuar. Conical, smooth; base carinated : 
volutions concave above, convex below; mar- 
gin and base striated. 
Somewnar related to the British Trochus Ziziphinus, 
but taller, smoother, and having the upper half of each 
whorl concave, the other half being concealed; the 
edge is obtuse, faintly marked with elevated striez ; the 
strie upon the base are strongest towards its centre; 
aperture rhomboidal ; umbilicus elosed. 
Found in the Crag of Suffolk, by Professor Sedgwick; 
the shell is very tender, and still retains much of its 
original pearly lustre beneath its opaque coat. 
TROCHUS imbricatus. 
TAB. CCLXXII.— Figs. 3 and A. 
Spec. Cuar. Pyramidal, with several transverse 
threads upon each whorl, crossed by fine lon- 
gitudinal striz, whorls angular, imbricating, 
flat above, very convex beneath. 
Auwosr half as tall again as wide: the angular shape of 
the volutions gives the spire the form of a screw; the 
base is very convex, and striated in the same manner as 
the rest of the shell; umbilicus closed. 
Found in clay near Cheltenham by Miss E. Warne, 
to whom I am indebted for the only specimen I have 
seen. 
QD s 4 eae 
Vez. % Kuviny. 
