204 Chatwin: Cretaceous Lamellibranchia of Yorkshire. 
made by the axis of growth with the hinge-line, and the pro- 
portionate length of the hinge with the height of the shell, as 
seen in the series J. labiatus, I. labiatus var. latus, I. inconstans, 
and J. balticus. 
To return to the Yorkshire Inocerami, however, we find that 
the earliest determinable forms occur in the Red Limestone 
(Albian): of Speeton, and their names J. sulcatus, Parkinson and 
f. tenuis, Mantell, still stand. I. concentricus, Parkinson, 
a species found very commonly in the Albian of other parts of 
England, is not recorded in the Monograph from Yorkshire. 
Mantell’s J. mytilloides, which has a wide distribution in the 
cuvieri-zone, and which was found by Dr. Rowe on the York- 
shire Coast, is now to be called J. labiatus Schlotheim. In the 
Chalk of the cortestudinarium-zone of Wharram has been 
found the important J.imconstans Woods, a new species founded 
on Mantell’s I. brongniarti var. The value of this new species 
can be seen by its connecting the narrow and high low-zonal 
lahiatus with the long-hinged balticus. Four species described 
by Goldfuss occur in the Upper. Chalk of Yorkshire, cvippsi 
{non Mantell), lobatus, lingua, and cardissoides ; . the last three 
names now stand, but Bohm’s balticus should be used instead 
of Goldfuss’s crippsi. 
One new species from the upper Chalk is described, 7. 
tuberculatus Woods, a form allied to J. lobatus, and resembling 
also I. cardissoides Schroder. Another ribbed form, which 
occurs in the quadratus-zone near Sledmere, has been found to 
be the same as a specimen from Brighton, to which Willett’s 
name J. pinniformis has been applied. Three Chalk species of 
another group remain to be mentioned. Inoceremus lamarcki 
Parkinson, found on the coast, and ranging from the cuvieri 
to the coranguinum-zones, is perhaps the commonest species 
in the chalk ; its synonymy occupies three pages of the mono- 
graph. It is the same as the brongniarti of Mantell and of J. 
Sowerby, and its variety cuviert, J Sowerby, is the gigantic 
form that is seen in long pieces in section and in a fractured 
state in the chalk, and used to be regarded as a separate 
species. Inoceramus lamarcki passes into I. involutus, J. de C. 
Sowerby, for which a separate genus Volviceramus was estab- 
lished by Stoliczka, but which now will not be used. J. 
cordiformis, J. Sowerby, a species like I. lamarcki, but distin- 
guished by the presence of radial folds, has been recorded 
from the cortestudinarium-zone of Wharram Percy. 
The foregoing list should include most of the Cretaceous 
Lamellibranchs of Yorkshire, and a brief account of the result 
must take the form more or less of the hurling of facts. It is 
hoped, however, that these notes may prove of service in the 
revision of names in collections, and in drawing attention to 
the results of a work that may not be easily accessible. 
Naturalist 
