254 Rev. O. Fisher—Thickness of Marine Deposits. 
whorl free, the rest only just in contact; whorl subcircular in 
section in the young, subquadrate in the adult; periphery convex in 
the free portion, concave in the last whorl and about one-half of the 
width of the side exclusive of the umbilical slope; sides flattened ; 
surface of the young shell, also the inner and a portion of the outer 
whorl ornamented with longitudinal, mostly crenulated, lines; the 
last whorl bearing backwardly-directed, transverse, sigmoidal lines 
of growth, which form a deep, backwardly-directed, subangular 
sinus on the periphery. Septa and siphuncle not observed. 
Discites Hibernicus, sp. noy., Lower Carboniferous Limestone, near Dublin.— 
A, lateral view of the type-specimen ; natural size. 
B, peripheral view of the same ; natural size. 
C, lateral aspect of the portion of the whorl between the letters a and d in A ; 
somewhat enlarged. ¢ 
D, the portion of the periphery between the letters ¢ and d in A; somewhat 
enlarged. 
V.— On ror Tuickness, Expansion, AND ResuLTInG ELEvaATIon 
oF Marine Deposits. 
By the Rev. 0. Fisuzr, M.A., F.G.S. 
HEN one refers back to such a paper as that by Babbage on 
the Temple of Serapis at Pozzuoli,’ one feels humiliated by 
the little advance which has been made in certain branches of 
dynamical geology within the last sixty years. That paper contains 
a full and elaborate account of the plan and history of the Temple 
and of the remarkable changes of level which its site has under- 
1 Read March 12, 1834; under which date see full abstract in Proc. Geol. Soc. 
vol. ii. p. 72. For paper in full see Journ. Geol. Soc. vol. iii. p. 186. 
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LS —— er ee 
