70 
Greville, on New Diatoms. 
Hah. Barbadoes deposit,, from Cambridge estate; C. John- 
son, Esq. 
The section containing those species which have the pro- 
cesses seated on an inflated portion of the disc is so limited 
that there can be no hesitation in considering the one now 
before us as new. It is more frequent than any other in the 
particular sample of the deposit which has furnished so 
many novelties. There are also at least three other Aula- 
codisci about the same size with which it is associated^ and 
which are inflated beneath the processes. One of them is 
the species next described. In another the inflations are 
further removed from the margin^ and are extended in an 
oblong form nearer to the centre. In the third the inflations 
are more or less rough with tubercles or apiculi^ as in 
A. Peter sit, and the margin is besides distinguished by a 
circle of gland-like tubercles. 
Aulacodiscus mammosus, n. sp., Grev. — Disc very promi- 
nently buUate beneath the processes^ the bullations close to 
the margin and forming elevated cones ; processes long, cylin- 
drical ; furrows open, composed of two parallel rows of gra- 
nules reaching the umbilical blank space. Diameter -0038". 
(Fig. 13.) 
Hab. Barbadoes deposit, from Cambridge estate ; C. John- 
son, Esq. 
This species may be known at once by the cone-like in- 
flations, which are so elevated as to be completely out of 
focus when any other part of the disc is examined ; and they 
rise so suddenly, and the sides are so steep, that it is impos- 
sible, in a vertical view, to see the structure. Having been 
so fortunate as to discover a valve exhibiting a front view, 
I am able to give the height of the bullation above the 
surface of the disc, which is about -0010", and, including 
the long cylindrical processes, -0012" ! Indeed, they may 
be not unaptly compared to thimbles. The ridges on 
which the furrows are situated commence near the centre 
with two parallel lines of granules, and gradually dilate, so 
that, including the bullation (as viewed vertically), the whole 
resembles in outline a child^s wooden battledore. On each 
side of the ridge the granules are so arranged as to appear 
like a fringe of diverging lines, while those on each side of 
the bullations become widely radiating. 
Aulacodiscus Kilkellyanus, n. sp., Grev. — Disc with (3) 
spherical, sub-marginal processes, and distant radiating lines 
of minute granules, 7 or 8 in '001", many of the lines not 
reaching more than half way towards the centre ; intra- mar- 
ginal strise 31 in -001". Diameter about -0040". (Fig. 14.) 
