488 A. Smith Wooduward— On the Genus Anomeodus. 
upon the caudal region. It has thus been suggested! that the species 
might be more appropriately placed in the typically-Cretaceous venus 
Celodus ; and at the same time it has been recognized that there is 
no essential generic difference between the form of dentition known 
as “Gyrodus angustus” and that from Maastricht, described by 
Agassiz, under the name of Pycnodus subclavatus. No splenial bones 
of the latter have hitherto been discovered sufficiently well preserved 
to show whether or not they possess the toothless border so charac- 
teristic of the species from Sussex ; but if any reliance can be placed 
upon the agreement in the arrangement of the teeth the generic 
identity of the species G. angustus and P. subclavatus may be deter- 
mined with as much certainty as can be attained in the classification 
of fragmentary Pycnodont remains. 
To decide upon the accuracy of this identification or otherwise is 
important, because six years ago the dentition commonly known as 
Pycnodus subclavatus was described by Forir? as indicating a pre- 
viously unrecognized distinct genus, Anomeodus; and the sole 
definition was based upon the arrangement of the splenial teeth. 
If, now, the universal belief that “ Gyrodus angustus”’ and ‘‘ Pycnodus 
subclavatus” are generically identical, be correct, new evidence is 
forthcoming to render the definition more satisfactory. So far as the 
arrangement of the splenial teeth in Anomeodus is concerned, there is 
no essential point to distinguish it from the Jurassic genus J/esodon; 
but on examining the attached face of the bone (e.g. A. superbus, 
Pl. XVI. Fig. 5a), the form will be seen to be quite different from 
that of Mesodon (Pl. XVI. Fig. 6), the first being shaped as in 
Pycnodus with a single sharp ridge curving to the postero-external 
angle, the second having a broad, longitudinally-grooved ridge not 
so sharply turned outwards. As regards the comparison with 
Celodus, it may be remarked that the difference in the arrangement 
of the splenial teeth is too great to render generic identity probable. 
We therefore assume that the provisional arrangement adopted by 
Forir will eventually prove correct, and that the characters of the 
splenial bone, now known only in two British Cretaceous species, 
will be shown by later discoveries to be common to the others. 
On this assumption the following preliminary diagnosis may be 
hazarded :— : 
Genus Anoma@ovpvs. 
Head-bones ornamented with reticulating ruge; the smaller teeth 
usually with an apical indent, the principal teeth quite smooth or 
with a very feeble linear indent. Vomerine teeth in from three to 
five longitudinal series; splenial dentition restricted to a space con- 
siderably separated throughout its extent from the thin oral border 
of the bone, comprising one principal series of teeth, flanked within 
by at least one small series and outside by two or more small 
series. Scales robust, confined to the anterior part of the trunk in 
advance of the median fins, and ornamented with reticulating ruge. 
1 K. A. von Zittel, ‘‘ Handbuch der Paleontologie,”’ vol. iii. (1887), p. 249. 
® H. Forir, ‘‘ Contributions a |’ Etude du systéme Crétacé de la Belgique,” Ann. 
Soc. Géol. Belg. vol. xiv. (1887), Mém. p. 25, Also ibid. vol. xvi. Mém. p. 445. 
