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GEOLOGICAL MAGAZINE. 
NEW SERIES. DECADE II. VOL. VII. 
No. V.—MAY, 1880. 
ORIGINAL ARTICLES. 
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I.—NotEes on THE ANOMALOCYSTID™, A REMARKABLE FAMILY oF 
OyYsToOIDEA, FOUND IN THE SiLuRIAN Rocks or Norta AMERICA 
AND BRITAIN. 
By Henry Woopwarp, LL.D., F.R.S., F.G.S.; 
of the British Museum. 
(PLATE VI.) 
YWENTY-TWO years ago, Mr. E. Billings, F.G.S., the late 
excellent paleontologist to the Geological Survey of Canada, 
completed and published Decade iii. of his “ Figures and Descriptions 
of Canadian Organic Remains” (Montreal, 1858), containing an 
admirable monograph on ‘the Cystidez of the Lower Silurian 
Rocks of Canada,” wherein (at pp. 72-74) he gives a clear and 
concise account of a very extraordinary fossil Cystidean, with a very 
poor woodcut figure of one side, the plates of which he clearly 
describes. To this fossil he gave the name of Ateleocystites Hualeyi. 
The specimen was obtained from the Trenton Limestone, near 
Ottawa, Canada. (See our Plate VI. Fig. 1.) 
Following immediately upon this Canadian Memoir appeared, in 
1859, the third volume of Prof. James Hall’s magnificent work, the 
Paleontology of New York ; wherein (at p. 182) he describes a new 
genus of Oystoidea, closely related to the above, under the name of 
Anomalocystites. ‘Two species are described by Prof. Hall, namely, 
A. cornutus (op. cit. p. 138, pl. vii. A. figs. 5-7), from the Pentamerus 
Limestone, Lower Helderberg group, Litchfield, Herkimer Co., and 
A. disparilis (op. cit. p. 145, pl. Ixxxviii. figs. 1-4), from the Oriskany 
Sandstone, Cumberland, Maryland. (Pl. VI. Figs. 2-5.) 
In 1859 Prof. James Hall (Paleontology of New York, vol. iii. 
p- 182) thus described his genus Anomalocystites: 
“Body semielliptical or semiovoid, sides unequal; the vertical 
outline oval or ovoid, plano-convex, or concavo-convex; the trans- 
verse outline semielliptical, the base of which is straight or more 
or less concave; the two sides composed of an unequal number of 
plates. Basal plates, three on the convex side, two on the concave 
side: second series, two large plates at the angles, and four (or 
five ?) on the convex side: third series, four on the convex side 
one at each angle, and a large plate on the concave side: a fourth, 
fifth, and sixth series of plates on the convex side, and a fourth 
series on the concave side. Base oblique, with the convex side 
longer, and a deep concavity for the insertion of the column. 
DECADE II.— VOL. YII.—NO. V. 13 
