pillar numerous, and those at the base thicker and more 
external (M. fulmineus, Lam. elegans, En. Meth. 862, 3.), 
the ventricose shape of some (O. undata, inflata, Lam.), 
the spire often concealed by a vitrious covering, and even 
the colours of others (M7. tessellata, guttata) remind us of the 
typical Volutes. It is very remarkable, that in most of the 
cylindrical Olives, the apex is more or less, papillary: the 
last complete terminal volution of the spire being thick, 
inflated, and distorted : (see particularly O. reticularis, En. 
Meth. 36, f. 1; fusiformis, Ub. 367, 1; guttata, Ib. 368, f. 2.) 
Others are seen of a more slender form, as O. subulata, 
LL. acuminata, EK. M. 368, 3, where the pillar is similarly 
plaited. Butin several small species allied to O. conoidalis, 
another modification of form has evidently commenced : the 
spire is regularly acute; the upper plaits disappear; and 
those which remain, are only at the thickened base of the 
pillar: the aperture, no longer narrow, becomes wide at the 
base, where the pillar takes an oblique direction inward ; 
we are thus led to the form of O. hiatula, KE. M. pl. 368, f. 5, 
where the characters of Ancillaria become apparent in the 
effuseness of the mouth, the double belt at the base, and 
the imperfect groove on the outer side of the pillar. Whe- 
ther we look to this shell, or to the descriptions given 
by Lamarck of the fossil species plicaria, canalifera, and 
laumontiana, or finally, to the Ancillaria glandiformis, Sow. 
no doubt can remain of the genus Oliva being here blended 
with the Ancillariw. There is, however, another form 
among the Olivz, which deserves mention, as it cannot well 
be associated with either of the preceding: this we have 
described below. Another genus that may be thought 
connected with Oliva, is Terebellum: a group very ably 
illustrated by Mr. G. Sowerby, in his ‘“ Genera of Shells.” 
To that work we must refer the reader for those reasons 
which shew its more immediate relation to Ovula. It is, 
in short, one of those forms too hazardous to class without 
a complete knowledge of the animal. 
eee 
OLIVA. striata. 
Shell small, cylindrical, sub-effuse, distinctly marked by regular 
longitudinal striz; upper part of the body whorl with one, 
lower part with four, belts; spire short, channelled, sub- 
papillary, naked; base of the pillar striated and externally 
detached by a groove. 
29 
Ancillaria canalifera? ? Lam. Syst. 7, 415. 
We do not find this fossil clearly described. Our speci- 
mens appear to be from the London clay. Its form seems 
analogous to Conohelix among the Mitres. The line ad- 
joining the figures denotes the natural length of the shells, 
