82 
Greville_, on New Diatoms. 
AULACODISCUS. 
Aulacodiscus decorus, n. sp._, Grev. — Large^ coloured ; disc 
with numerous (about six) submarginal processes ; furrows 
open_, defined by parallel lines of granules^ terminating in 
very small blank spaces surrounding the processes ; granules 
minute^ irregularly disposed in the centre, soon passing into 
closely moniliform slender lines, with intermediate shorter 
ones. (Fig. 2.) 
Hab. Barbadoes deposit, Cambridge estate; C. Johnson, 
Esq. 
A fine large species, without any umbilical space, the 
centre being filled up with somewhat remote and irregularly 
scattered, minute, spherical granules, which soon arrange 
themselves into long slender lines, strongly marked by the 
brownish colour of the closely placed granules. As the lines 
proceed towards the margin there is no appearance of dicho- 
tomous division in order to fill up the increasing space ; but 
shorter lines are introduced like the gills of many Agarici, and 
furnish a conspicuous character. This arrangement, however, 
is irregular, as several long lines are sometimes continued 
side by side to near the margin, while in other cases the 
shorter lines occur more frequently. In this character our 
present species is allied to 'A. Kilkellianus. The diameter of 
the disc is from -0060^' to -0080". 
AULISCUS. 
Auliscus Normama7ius, n. sp., Grev. — Very large; valve 
circular, with a large smooth umbilicus, and very fine, close, 
radiating, plumose lines ; a row of submarginal puncta, and 
numerous apiculi scattered over the outer parts of the disc ; 
processes 3, large. (Fig. 11.) 
Hab. Deposit at Moron, province of Seville; George 
Norman, Esq. ; C. Johnson, Esq. 
A splendid, well-marked, and rare fossil species. It appears 
to be strictly circular, and may be distinguished at a single 
glance by the submarginal row of puncta, combined with the 
scattered apiculi which are considerably more numerous 
than those in the disc of Aulacodiscus scaber. The lines 
which converge from the centre to the processes are very 
numerous and delicate, but sharp and distinct ; those which 
radiate to the circumference exceedingly fine and faint. In 
the example figured, the processes are situated at a con- 
siderable distance from the margin, but this is not a constant 
