Note on tlie Genus Anthrapalcemon. 
55 
to the interspaces of the teeth in the median row. Tlie outer row 
on the right side (PI. IV. Pig. 2 d) has four teeth, one vacancy and 
an anterior circular tooth, similar to the small circular tooth of the 
median set. All the teeth on the left side are broken away except 
the anterior one (PI. IV. Fig. 2 e) and a small irregulär tooth, similar 
though smaller than those in the median and right outer ranks. 
These teeth are oval on their inner periphery, but truncated along 
the maxillary border. All the teeth in this specimen which have 
not been ground down by use have a shallow depression in the centre 
of each tooth, over which the outer coat or layer of ganoine is spread 
in minute folds radiating from the centre. This type of tooth, as I 
have before explained, is easily distinguishable from the dentition of 
Gyrodus. 
As there is no instance on record of the occurrence of a Sheppey 
Pycnodont with the upper and lower masticating apparatus so 
associated as to render it probable that they were derived from the 
same individual, it is impossible to determine whether the specimen 
here described should be assigned to Pycnodus toliapicus or to 
Pycnodus Bowerbanki, or to neither. The light thrown upon the 
subject by the examination of other species in which the dentition 
is accurately known, leads to the conclusion, that the median 
vomerine teeth agree in general character with the large mandibular 
teeth, but are more obtuse in outline. If this be so, this vomer is 
more nearly related to Pycnodus toliapicus than to Pycnodus Bower- 
banki ; at the same time in other respects it so far differs that I 
must hesitate to consider it as referable to that species. The most 
striking character of this interesting relic is the extraordinarv mo- 
dification of the facial anatomy for affording power to work the 
masticating apparatus, and suggests to me the provisional name of 
Pycnodus pachyrhinus. 
EXPLANATION OF PLATES III. AND IY. 
Plate III. Fig. 1 . — Coelodus ellipticus, Egerton. Right mandible. 
„ Fig. 2. — Pycnodus Bowerbanki, „ Right mandible. 
Plate IY. Fig. 1 . — Pycnodus pachyrhinus, ,, Yomer. Profile. 
„ Fig. 2. — Pycnodus pachyrhinus, ,, Vomer. From below. 
„ Fig. 3. — Coelodus gyrodoides, „ Yomer. From below. 
II. — Note on the Genus A nthrapa ljsmo.y ( Paljeocarabus ) of 
SaLTEB, FBOSI THE CoAL-JIEASUBES. 
“The earliest known example of a fossil Macrourous Decapod 
Crustacean was obtained by Prof. Prestwich from the Pennystone 
Ironstone of the Coal-measures, Coalbrook-dale, Shropshire, and was 
at that time referred by Prof. H. Milne-Edwards, who examined it, to 
the Phyllopoda under the name of Apus dubius (see Trans. Geol. Soc. 
Lond., 1836, 2nd series, voL v. p. 413). In 1844 some further re- 
mains of this genus were noticed by W. Ick, Esq., F.G.S. (see Quart. 
Journ. Geol. Soc. Lond., vol. i. p. 199). We are indebted to the late 
Mr. J. W. Salter for the first correct account of these Crustacea in 
1861, when he figured the almost entire form from a specimen in 
the collection of Dr. William Grossart, obtained in the * slaty black- 
