223 
TROCHUS, Linn. &c. 
Gen. Cuar. Univalve, spiral, conical; base flat 
or concave; aperture transversely depressed, 
subquadrangular; axis oblique. 
Serene ts 4:0 So, eee 
W aorts more or less carinated, the keel of the last form- 
ing the margin of the base. Some species are umbilicate 
when young, the umbilicus being covered in old shells; in 
other species the umbilicus is permanent, and some have a 
solid columella. The Phorus of Montfort may, perhaps, 
hereafter prove a good Genus, but the variable umbilicus 
and the agglutinating practice of the animal are too uncertain 
for generic distinctions. The other characters are found to 
be gradually shaded off when we examine many species. 
TROCHUS agglutinans? 
TAB. XCVUI.—Smaller figures. 
Spec. Cuar. Depressed, conical, smooth; base 
expanded, with a broad waved margin; whorls 
externally deformed; umbilicus plicate; aper- 
ture oblong. 
Syn. Trochus agglutinans? Delamarck, Foss. des 
environs de Paris, p. 102. ; 
T. umbilicaris. Brander, Foss. Hant. figs. 4 &5. 
Phorus aggiutinans. De Montfort, 2. 158. 
A A eee EERE eee 
Mocu irregularity in the upper surface and margin of this 
is produced by the shells and fragments of other substances 
that become attached to it, which has procured it from 
some the appellation of ‘‘ the Conchologist,” from others, 
that of ‘¢ the Builder,” ‘the Carrier,” &c. The smooth, 
uninterrupted part of the surface is only marked by striz of 
