TEREBELLUM. TRACHELIPODA. 27 
rated by a narrow canal, above which the volutions are 
coated with a fine enamel ; aperture elongated, rather nar- 
row, and notched at the base; columella obliquely striated 
or plaited, its base provided with an oblique, somewhat 
tumid, striated, varix-like appendage. 
Oliva Salisburniana. Plate III. fig. 10. Found in the 
London clay. 
The shells of this genus bear a considerable resemblance to those of Ancil- 
laria, but are readily distinguished by the canaliculate suture which separates 
the volutions, as well as by the striated columella; they are also recognized 
from the Volute and Mitre by the same characters. 
All the Olive are marine shells, principally natives of tropical climates, 
None are found in the British Seas. 
But few fossil Olive are known; these are found in the London clay and 
Calcaire-grossier ; and one species occurs in a sort of Greensand, near Turin 
Genus III. — ANCILLARIA. — Lamarck. 
Generic Character. — Shell oblong, subcylindrical ; spire 
short, seldom more than a third of the length of the shell, 
the suture is not canaliculate, and is generally obscured by 
a coating of enamel, which frequently covers the whole 
spire; aperture longitudinal, narrow above, effuse and 
notched at the base ; lower portion of the columella smooth, 
with an oblique tumid, usually striated varix at the base ; 
entire outer surface smooth and glossy, supposed to be 
devoid of both epidermis and operculum. 
The columella being devoid of plaits, distinguishes the shells of this genus 
from those of the genus Oliva; and the callous, oblique band at the base of the 
columella, separates them from those of the genus Terebellum; they have 
sometimes been mistaken for a species of the genus Melanopsis which are 
invariably fresh-water shells, more particularly the fossil species; but the 
latter genus may readily be distinguished, by the tumid upper portion of its 
pillar lip, and by the spiral line being distinct, and in the outer surface not 
being polished. 
Ancillaria subulata. Plate III. fig. 83. Found in the 
upper marine formations. 
The Ancillaria are marine shells, ‘and principally inhabitants of tropical 
climates. The fossil species are very limited in number. They chiefly occur 
in the London Clay, Calcaire-grossier, and Greensand. 
Genus 1V.— TEREBELLUM.— De Montfort. 
Generic Character.— Shell thin, convolute, subcylindrical, 
rolled around its longitudinal axis in the form of an elon- 
gated cone ; spire short, sometimes hidden ; aperture longi- 
tudinal, narrow above, and ascending in the form of a 
straitened spiral canal, defining the volutions ; the outer lip 
entire, and not thickened, diverging as it descends, widely 
