44 
Greville^ on the genus Auliscus. 
tuSj as compared with A. C(slatus, are as follow : — 1. The form 
is usually circular^ while in A. ccelatus it generally tends to 
oval. 2. The lateral depressions are deeper. 3. The costse 
within the depressions are strongs nneqnal, not radiating 
symmetrically, like a fan_, but generally pointing in different 
directions, and apparently terminating abruptly before reach- 
ing the outer curved edge of the depressions. 4. A much 
greater tendency in the costse of the depressions to anasto- 
mose. 5. The entire absence of apiculi. This character, 
although a minute one, seems to be of importance. I have 
examined very many examples of A. ccelatus, and never found 
apiculi wanting, excepting in one instance, which I have 
given at fig. 7. Occasionally there are, in A. sculptus, a few 
narrow, transverse cellules, formed by anastomosis, just be- 
neath the outer curve of the depressions; and sometimes a 
transverse costa is visible, following the line of the ridge 
below its summit, from which branch off at right angles the 
strong costse which proceed to the margin. This transverse 
costa is probably always present, concealed within the margin 
of the cavity, as the marginal costee are certainly not (all of 
them, at least) continuations of those within the depressions. 
Mr. Ralfs, under A. ovalis, in Pritchard, remarks — The 
truncated processes do not, in general, correspond exactly 
with the longer diameter of the valve, but are placed a little 
on one side in opposite directions." This I have ascertained 
to be the case in all those species which deviate from the 
circle. If a straight line be drawn through the middle of 
the valve in its longest diameter, the two processes will in- 
variably be seen more or less on the opposite sides of the 
line ; and such is the rule with our present species itself, 
whenever it assumes a slightly oval form. 
Auliscus ccelatus, Bail. — Valve slightly inclining to oval 
(most rarely circular), with indistinct umbilicus ; radiating 
costse next the margin, strong, distant ; central area 4-lobed, 
2 of the lobes composed of finer costse converging to the pro- 
cesses ; the intermediate lobes depressed, containing radiating, 
often more or less anastomosing lines, and studded with 
minute apiculi, which are sometimes confined to the outer 
edge of the lobes. Diameter -0022" to -0065". (Figs. 4—7.) 
Auliscus ccelatus, Bail. — Notes on New Species of Mic. 
Organ.^ (^ Smithson. Contrib.,^ vol. vii), p. 6, figs. 3, 4; Ralfs, 
in Pritch., 1861, p. 845. 
Hab. In sand washed from West India sponge, and in 
soundings from Mobile Bay, U.S. ; Prof. Bailey. Mud from 
New London Harbour ; Delaware River mud, rare, U.S. ; Dr. 
Iiewis. Californian and Ichaboe guanos, C. Johnson, ^Esq._J 
