﻿THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE II. VOL. IV. 



No. VI.— JUNE, 1877. 



I. — Further Contributions to British Carboniferous 



Paleontology. 



By E. Etheridge, Junior, F.G.S. 



(PLATE XII.) 



Class Lamellibranchiata. Genus Pecten, Bruguiere. 



Pecten (Amiissium ?) Soioerhii, M'Coy. Plate XII. Figs. 1-3. 



N the GtEological Magazine for July, 1874,^ I gave a description 

 and figures of this species, and also that of a shell I referred 

 with some hesitation to Aviculopecten ellipticus, Phillips, closely re- 

 sembling the forms referred to P. Sowerhii, but differing in the form 

 of the ears, which are after the normal type of the Pectimdce, and not 

 connate, with a re-entering angle between them, as in P. Sowerhii. 

 In the above description, and in a note succeeding it,^ I stated that I 

 had seen traces of the characteristic V-strise of P. Sowerhii on the 

 shells referred by me to A. ellipticus. I had at the time some doubts 

 in my own mind as to the propriety of the reference of these shells 

 to A. ellipticus, Phill., and now, after consideration and examination 

 of a further large series of specimens, I am convinced that the shell 

 I figured as A. ellipticus is nothing more than the opposite valve of 

 P. Soioerhii, M'Coy; and that I was too hasty in placing it under the 

 name of Phillips's shell. In other words, one valve of P. Sowerhii 

 has the ears connate, with a re-entering angle between them, and the 

 shell very frequently showing the v-strias (Fig. 1) ; the other has the 

 ears after the usual form, and the shell only occasionally showing 

 the peculiar striee (Figs. 2 & 3). Both forms are constantly associated 

 together, often to the exclusion of other members of the Pectinidcs, 

 and they exhibit several characters in common with one another, 

 such as puckering or shrivelling of the shell, the lateral grooves 

 from the beaks, and the ears, although differing in form, still striated 

 similarly. If a glance is given at one of my former figures,^ a point 

 I then neglected to draw attention to will become apparent, viz. 

 that there is a decided indication in the ears of the figure that the 

 specimen represents the compressed valves in apposition. My 

 colleague, Mr. W. Hellier Baily, has given a figure* of this species 

 which corroborates mj?- reading of the subject. His figure exhibits 

 the simple small ears, and the shell without v-striae, but having some 



1 Dec. II. Vol. I. p. 300, PI. XIIT. Figs. 1 and 2. ^ p_ 304. 



3 I.e. PL XIII. Fig. 1. i Figures Char. Brit. Foss., vol. i. pi. 39, fig. 3. 



DBCADB II. — VOIi. IV, — NO. TI. 16 



