Messrs. Foord and Orick—On Discites Hibernicus. 2Zol 
we have to do not with a specific variation but with an abnormality 
produced by something interrupting the secreting action of the 
mantle: whether this was a foreign substance, a parasite, a disease, 
or a constantly recurring similar accident, I have not sufficient data 
at present to decide. As far as I know no similar series of forms 
has been elsewhere described ; and in the Woodwardian Museum 
we have none from any other locality. 
EXPLANATION OF PLATE IX. 
(The figures are numbered to indicate the successive stages in the development of 
the abnormal features as exhibited in the series of specimens of Spirifera lineata 
from the Carboniferous of Settle.) 
Figs. 1, 1a. Dorsal and ventral aspects. First and earliest stage. 
aise or Ventral aspect. 
», 9, 8a. Dorsal and ventral aspects. 
op to Anterior aspect. 
5. Ditto. ditto. 
», 6, 6a. Dorsal and ventral aspects. 
np lo Anterior aspect. 
8, 8a. Dorsal and ventral aspects. 
9,9a, 96. Dorsal, ventral, and anterior aspects of the most abnormal specimen. 
” 
IVY.—Own a New Species or Discirzs (Discirzs HiBeRrnicus) FROM 
THE Lower CarBonrFEROUS LIMESTONE OF IRELAND. 
By Artuur H. Foorp, F.G.S.; and G. C. Crick, Assoc.R.S.M., F.G.S., 
of the British Museum (Natural History). 
HE specimen which forms the subject of the present communica- 
tion was obtained by one of the writers from the Carboniferous 
Limestone, near Dublin. Although one side of the specimen is 
covered by matrix, yet the other side and the periphery are so 
splendidly preserved, and the shell has not been distorted during 
fossilisation, that the characters of the fossil can be accurately 
determined (see Woodcut, p. 254). 
The specimen belongs to M‘Coy’s genus Discites, but differs, so 
far as we have been able to ascertain, from any species hitherto 
described. 
The shell is discoid, compressed laterally, and composed of rather 
more than two volutions, which increase rather slowly in diameter. 
The extreme tip of the shell, possibly a length of about one milli- 
metre but not more, has been broken off in developing the inner 
whorl from the matrix. The apex is bluntly pointed, and the 
whorls begin in a wide curve which is free to the extent of about 
halt a volution, from which stage the outer whorl comes in contact 
with the inner for the rest of the growth of the shell. Thus the 
young shell to the extent of about half a volution is simply curved. 
The transverse section of the free or earlier portion of the shell 
is subcircular, becoming in the outer whorl subquadrate with the 
lateral angles rounded. he sides are flattened, and in the second 
whorl a well-marked, shallow depression occupies the outer half of 
the lateral area. The peviphery is sulcate, bounded on each side by 
a subangular ridge, and is about one half the width of the side 
