﻿Note on the Genus Anthrapalcemon. 55 



to the interspaces of the teeth in the median row. The outer row 

 on the right side (PL IV. Fig. 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 (PL IV. Fig. 2 e) and a small irregular 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 Bowerhanki, 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 toUapicus than to Pycnodus Bower- 

 hanlci ; 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 extraordinary mo- 

 dification of the facial anatomy for affording power to work the 

 masticating apparatus, and suggests to me the provisional name of 

 Pycnodus pachyrhinus. 



EXPLANATIOlSr OF PLATES III. AND IV. 



Plate III. Fig. 1. — Coslodus ellipticus, Egerton. Eight mandible. 



,, Fig. 2. — Fyenodus Bowerhanki, ,, Eight mandible. 



Plate IV. Fig. 1. — Pycnodus pachyrhinus, ,, Vomer. Profile. 



,, Fig. 2. — Fyenodus pachyrhinus, „ Vomer. From below. 



„ Fig, 3. — Ccelodus gyrodoides, „ Vomer. From below. 



II. — Note on the Genus Anthrapal^mon [Pal^ocarabus) of 

 Salter, from the Coal-measures. 



"The earliest known example of a fossil Macrourous Decapod 

 Crustacean was obtained by Prof. Prestwich from the Penny stone 

 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 Ajjus dubius (see Trans. Geol. Sue. 

 Lond., 1836, 2nd series, voL v. p. 413). In ISM 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- 



