176 Mr. UH. Seeley on new and little-known Fossils 
diameter. There are on the sides of a whorl about cight or nine 
narrow flexuous ribs but little elevated and only appearing on the 
outer or converging parts of the sides. The back is perfectly 
rounded into the ches so that it cannot be said to have a limit. 
The septa are complicated, apparently with many saddles and 
lobes. 
I suppose this shell to be that hitherto included in Hunstanton 
lists as A. complanatus (Mant.), with which it has no near affinity, 
rather recalling the A. bicurvatus of Michelin ; but its nearest re- 
lations appear to be with A. Austini (Sharpe), pl. 12, Paleont. 
Cret. Moll., from which it is distinguished by its small umbilicus, 
compressed form, and smooth shell, which at the utmost separate 
: asa variety. The A. alternatus of S. Woodward had a round 
ack. 
Ammonites proboscideus (Sow.). 
The species is given by Morris as from the Gault of Cambridge. 
I have neither found nor heard of it there. One specimen has 
been obtained from the Gault in the Ely pit. 
Nautilus simplex (Sow.). 
I only know this fossil by the figure of a cast in the ‘Min. 
Conch.;’ and with that this very beautiful Hunstanton fossil agrees 
in the straight distant septa and the size of the umbilicus. It cor- 
responds well, too, with Ooster’s figure. Externally it is much like 
N. Bouchardianus, for which recent figures of it might well pass. 
The two species are probably varieties of each other. 
Plicatula minuta (Seeley). 
A small shell attached by the umbo, with an oblique axis ; 
oue valve flat and the other convex. 
Length } inch ; width =, inch. 
Form ovate, lower valve moderately inflated. It is ornamented 
with numerous fine ribs, which radiate from the umbo, are some- 
times dichotomous, and vary greatly in the degree of their eleva- 
tion and continuity, occasionally appearing as pseudo-spines laid 
flat on the shell. The attached Es is generally small, and | have 
never seen it equal to a third of the length of the shell ; in the 
upper valve it produces a corresponding ‘elevation, which is gene- 
rally worn off, giving specimens the look of Anomic. The upper 
valve is flat or a little cone: we, sometimes very finely marked 
with radiating striz, otherwise imbricated. 
It might be supposed that this is the young of Plicatula in- 
flata; but the fact that specimens im the Cambridge Greensand, 
where it is not rare, all occur of the same size and quite resem- 
bling this of Hunstanton, seems to point conclusively to these 
being adult shells. 
