344 
KAniLOIDEA. 
mate ; sutures strongly curved forwards on the sides, starting from 
the umbilicus, and then sweeping backwards and almost touching 
those of the preceding septum ; they then bend forward again at a 
sharp angle, and continuing for a short distance in a direction parallel 
with that of the periphery, they pass over the latter at right angles 
to the last part of their course. The siphuncle is situated close to 
the dorsal margin. The test is quite smooth, having only very fine 
striae of growth ; in general only the nacreous layer is preserved. 
Bemarlcs. Aturia zicznc was first described by J. Sowerby from a 
specimen which was found during the construction of Highgate 
Archway. F. E. Edwards ^ describes it as “ a smooth, involute shell, 
Fig. 74. 
Aturia ziczac. — a, lateral view of the specimen (No. 32650) figured in Dixon’s 
‘ Geology of Sussex,’ pi. viii. f. 1 9 ; h, front view of the same : c, front view 
of a young specimen from Kressenberg, Bavaria (C. 2182) ; cf, lateral view 
of the same. Drawn from specimens in the British Museum. All of the 
natural size. 
more or less ventricose or depressed ; the septa are outwardly deeply 
concave ; and, owing to the regular curve in- which the dorsal lobes 
are reflected towards the axis of the shell, they present, when viewed 
sideways, some resemblance to the letter S ; the lateral lobes are 
more or less narrow, and taper rather suddenly towards the inferior 
extremit)’, which extends nearly to the preceding septum ; but they 
are without the sinus which characterizes the lateral lobes of Iscmt. 
{^Aturia\ Parlcinsoni. The English shells are generally either casts 
in, or filled with, pyrites. ...” 
^ Monograph of the Eocene Mollusca, pt. i. Cephalopoda, Mon. Pal. Soc. 
pp. 52-55. 
