52 
GrevillEj on the genus AuUscus. 
racier be permanent) by the presence of four processes. One 
other species belonging to this marvellous deposit has occurred 
both to Mr. Ralfs and myself with the same number ; and as 
those of the subjacent valve are nearly as visible as the four 
in the upper valve, there is the singular effect of a circle of 
eight processes. Our specimens of this latter species are all 
unfortunately more or less injured in the superficial sculpture. 
The plumose lines in A. Johnsonianus are even finer than in 
A. elaboratus, but are otherwise very similar, and have also 
the same very minute granular character. 
•K-^^-x- ^liole surface of valve widely reticulated. 
Auliscus Ralfsianus, n. sp._, Grev. — Valve circular, with the 
whole surface covered with a wide and lax network, the spaces 
within the interstices showing minute puncta, arranged in 
radiating and converging lines. Diameter "0045". (Fig. 21.) 
Hab. Barbadoes deposit (Cambridge estate); C. Johnson, 
Esq. 
Perhaps this may be considered as the most extra- 
ordinary species in the whole genus, and I have the greatest 
pleasure in dedicating it to my highly valued friend and fellow- 
labourer, Mr. Ealfs. In all the rest the prominent superficial 
sculpture is characteristic of the group ; the radiating or plu- 
mose arrangement of the lines, especially those which curve 
and converge from the centre to the processes, being more or 
less evident. But in the present case the observer is startled 
by, at first sight, perceiving nothing but a loose, wide, brown 
network enveloping the whole valve, with the exception of 
the processes. An attentive examination, however, shows 
that within the reticulations there are puncta or minute cel- 
lules, arranged in the manner common to the genus. The 
processes are almost marginal, nearly circular, and very large. 
The following species are unknown to me, and cannot be 4 
established without additional information : 
Auliscus Americanus, Ehr. — It is impossible to say what 
this may be from Ehrenberg^s figure (Microg. pi. xxxviii (14), 
fig. 2), which is doubtless incorrect, as no space is left for any 
converging lines between the centre and the processes. 
A. gigas, Ehr., Microg., pi. xix, fig. 63. A fragment too 
small and imperfect. 
A. cylindricus, Ehr. — No figure published. 
A. poly stigma {Coscinodiscus), Ehr., Bericht Berl. Akad., 
1844, p. 78. No figure published. 
