54 
MOLLUSCA. 
Several are flattened, with a trenchant edge, which has caused them 
to be compared to the rowel of a spur — Calcar, Montf.'* * * § ^ 
Some again are slightly depressed, orbicular and shining, with a 
semi-round aperture, tlie columella convex and callous — Rotella, Lam.| 
The columella of others is distinguished near the base by a little 
prominence, or vestige of a tooth, similar to that of the Moiuxlontes, 
from which these Trochi only difter in the angle of their aperture, 
and the projection of their margin. The aperture is usually about 
as high as it is wide — Cantliari^, ]Montf.| 
In some of them, on the contrary, the aperture is much wider than 
it is high, and their convex base approximates them to the Calyp- 
tracea — I')}fiindihulum,lslo\\\.f.^ 
In others again, where the aperture is also much wider than it is 
high, the columella forms a spiral canal||. 
Those which have a turreted shell aiiprcach Ccrithium — Telesco- 
■yiiim, Montf.^ 
Among the umbilicated Trochi, there are some in which there is no 
projection in the columella ; most of them are flattened, and have the 
external angle trenchant. Of this number is 
7V. ag(jlutinans, L. ; Chemn., V,clxxii, 1688, 9. Remarkable 
for the habit of glueing to its shell, and even incorporating 
with it, as fast as it increases in size, various foreign bodies, 
such as little pebbles, fragments of other shells, &c. ; it frequently 
covers its umbilicus with a testaceous plate**. 
The margin of others, however, is rounded, such as 
7V. cinerarius, L.; Chemn., V. clxxi, 1686. . A small species, 
and the most common on the coast of France; greenish, ob- 
liquely streaked with violet. 
Some umbilicated Trochi have a prominence near the bottom of 
the columella f f. 
And, finally, there arc others in which it is longitudinally cre- 
nate tt. The 
* Turbo calcar, L., Chemn., V. clxiv, 1552; — T. stellaris, Id., 1553; T. aculeutus, 
Id., 1554 — 57; — T. imperialis, Id., 1714. 
t Tr. vesfiarius, L., Chemn., V. cl.xvi, 1601. 
pi + Tr. iris, Chemn., 1522 — 23; — Tr. granutum, Ib., 1654 — 55; — Tr. zyzypMnvs, 
Ib., clxvi, 1592 — 98; — Tr. counts, clxvii, 1610; — Tr. maculatus, e\x\ih, 1617 — 18; — 
Tr. americanus, clxii, 1534—35 ; — Tr. comthis, Gualt., LXX, hi. 
§ Trochus concavus, Chemn., Y, cl.xxviii, 1620, 21. 
II Trochus foveol alas, Chemn., V, clxi, 1516 — 19; — Tr. manri/iuiius, Id., cLxiii, 
1547 — 48 ; — Tr. fenesirafus, Ib., 1549 — 50;— T/'. obeliscus, clx,'1510 — 12. 
^ Trochus telescopium, Chemn., V, clx, 1507 — 9. 
** Add, Trochus ludicus, Chemn., 'S'', clxxii, 1697 — 98; — Tr. ImjJerialis, clxxiii, 
1714, and clxxiv, 1715; — Tr. Solaris, Ib., 1701 — 1702, and 1716 — 1717; — Tr. 
j)lams, Ib., 1721, 1722. 
ft Tr. viryatus, Chemn., Y. clx, 1514 — 15; — Tr. niloticus, Chemn., Y. clxvn, 
1605 clxviii, 1614; — Tr. vernus. Id., clxix, 1625 — 26; — Tr. inccqualis, clxx, 
1636 — 37 ; — Tr. niagnus, cl.xxi, 1656 — 57 ; — Tr. consp)ersus, Gualt., Ixx. B.; — Tr. 
jtijubinus, clxvii, 1612 — 13. 
Tr. maculatus, clxviii, 1615 — 1616; — Tr. cosfafus, elxi.x, 163 1 ; — Tr. viridis, 
clxx, 1644; — Tr. 7-adiatus, Ib., 1640 — 42. 
