Greville^ on New Diatoms, 
71 
Hab. Barbadoes deposit^ from Cambridge estate; C. John- 
son, Esq. 
A remarkably distinct and beautiful species,, conspicuous at 
first sight for the open character of the disc, arising from the 
distance between the radiating lines, which, in regard to 
length, are divided into several series, like the gills in an 
Agaric. This is more or less the case in many of the species, 
but here it attracts attention on account of the comparatively 
small number of lines rendering the arrangement more visible. 
The processes appear to the eye to extend as far as the mar- 
gin. There is no bullation, and the connecting farrows are 
so similar to the other interlinear spaces that they do not 
form a prominent character. 
I have great pleasure, in accordance with the wish of my 
highly valued friend, Mr. Johnson, in bestowing upon this 
exquisitely beautiful diatom the name of — Kilkelly, Esq., 
of Barbadoes, to whose kindness Mr. Johnson was indebted 
for the material which has proved so rich in new genera and 
species, and which has enabled us to extend so considerably 
our knowledge of diatomic forms. 
Aulacodiscus angulatus, n. sp., Grev, — Valve elevated in 
the middle, and somewhat prismatic ; the centre depressed, 
with a blank umbilicus ; processes (5 or 6) without inflations, 
submarginal ; connecting furrows very narrow, on prominent 
ridges. Diameter about -0040". (Fig. 15.) 
Hah. Barbadoes deposit, from Cambridge estate; C. John- 
son, Esq. 
The most characteristic feature in this species is the ele- 
vated and somewhat angular form of the middle of the valve. 
The centre is flattened or depressed, and surrounded by a 
raised shoulder, from which the prominent furrow-bearing 
ridges radiate to the processes. The prismatic form of the 
disc will be best understood from the fact that when the 
glass is adjusted for the shoulder and ridges the intermediate 
compartments are quite out of focus. An additional angu- 
larity is also imparted in consequence of the portion of the 
raised shoulder which is left between the radiating ridges 
being carried in a straight line between ridge and ridge, a 
pentagonal or hexagonal efiect (as the case may be) being 
thus produced. The furrows are very narrow, the space being 
often less than the diameter of the granules themselves, ex- 
cept as they approach the processes. In the specimens which 
I have examined, the 'processes seem to have been all broken 
away, the roundish, blank spaces being quite flat. 
Aulacodiscus spectahilis, n. sp., Grev. — Valve convex, with 
the centre depressed, and a blank umbilicus ; processes (5) 
