File:The Quarterly journal of the Geological Society of London (13365241494).jpg

1849.. CARPENTER ON THE STRUCTURE OF NUMMULITES, ETC. 21
vey,' are not always to be found on specimens. The best examples
which I have seen of these extraordinary characters, are two fossils
in the museum of the Leeds Philosophical Society. These I first
observed in company wdth the late Mr. Bowman in 1839, when we
were both much struck with their appearance, and that gentleman
procured drawings of them, of which the present are reduced copies.
The specimens are composed of a fine-grained sandstone, and I be-
heve they were found in the coal-measures near Bradford, Yorkshire.
Figs. 5 and 6 represent
an under and a side view of Fig. 5. Fig. 6.
the larger of these fossils.
The greatest breadth mea-
sured across the suture is
2 feet 2 inches. The parts
of the roots remaining are
mere stumps, and show no
true characters of either Sigillaria or Stigmaria, bat are marked with
the irregular lines so generally found on decorticated specimens of large
Sigillariee, just like those on the Dixon Fold and St. Helen's trees.
Figs. 7 and 8 represent
the under and side views Fig. 7.
of the smaller of these
specimens. The greatest
breadth at the base across
the suture is 14 inches.
As part of the roots of
this specimen remain, we
see the same system of
dichotomizing which was
noticed in the Dixon Fold
and St. Helen's trees. At the extremities of both
roots are the usual areolae with a little elevation in
the centre and the convex corrugated lines so com-
mon to Stigmarige.
Fig. 9 gives a tolerable idea of the appearances
which in my opinion prove the specimen without
doubt to be a Sigillaria.
Fig. 8.
2. 071 the Microscopic Structure of Nummulina, Orbitolites,
and Orbitoides. By William B. Carpenter, M.D., F.R.S.,
F.G.S.
About five years since, I was requested by my friend Mr. S. P.
Pratt to endeavour to determine by microscopic examination the cha-
racter of certain discoidal bodies, varying from about four to ten lines
in diameter, which he had found in great abundance in the nummu-
litic deposits of Biaritz, and the nature of which could not be resolved
by any ordinary means. Their circular form and limited dimensions