THE 
GEOLOGICAL MAGAZINE. 
NEW SERIES. DECADE II. VOL. IV. 
No. VI.— JUNE, 1877. 
OIRIG-IIsr^AIIl ABTICLBS. 
I. — Further Contributions to British Carboniferous 
Palaiontology. 
By E. Etheridge, Junior, F.G.S. 
(PLATE XII.) 
Class Lamellibranchiata. Genus Pecten, Bruguiere. 
Pecten ( Amussium ?) Sowerbii, M'Coy. Plate XU. Figs. 1-3. 
I N tlie Geological Magazine for July, 1874/ I gave a description 
and figures of this species, and also tbat of a sbell I referred 
with soine hesitation to Aviculopecten ellipticus, Phillips, closely re- 
sembling tbe forms referred to P. Sowerbii, but differing in tlie form 
of the ears, which are after tbe normal type of tbe Pectinidce, and not 
connate, witb a re-entering angle between tbem, as in P. Sowerbii. 
ln tbe above description, and in a note succeeding it, 2 I stated tbat I 
bad seen traces of the cbaracteristic V-striai of P. Sowerbii on the 
sbells referred by me to A. ellipticus. I liad at tbe time some doubts 
in my own mind as to tbe propriety of tbe reference of tbese sbells 
to A. ellipticus, Pbill., and now, after consideration and examination 
of a further large series of specimens, I am convinced tbat tbe sbell 
I figured as A. ellipticus is nothing more tban tbe opposite valve of 
P. Sowerbii, M‘Coy ; and tbat I was too hasty in placing it under tbe 
name of Phillips’s sbell. In otlier words, one valve of P. Sowerbii 
bas tbe ears connate, witb a re-entering angle between tbem, and the 
sbell very frequently sbowing tbe v-striai (Fig. 1) ; tbe otlier bas tbe 
ears after tbe usual form, and tbe sbell only occasionally sbowing 
the peculiar striae (Figs. 2 & 3). Botli forms are constantly associated 
together, often to tbe exclusion of other members of tlie Pectinidce, 
and tbey exbibit several cbaracters in common witb one another, 
such as puckering or sbrivelling of tbe sbell, tbe lateral grooves 
from the beaks, and tbe ears, although difiering in form, still striated 
similarly. If a glance is given at one of my former figures, 3 a point 
I tben neglected to draw attention to will become • apparent, viz. 
that. tbere is a decided indication in tbe ears of tbe figure tbat the 
specimen represents tbe compressed valves in apposition. My 
colleague, Mr. W. Hellier Baily, bas given a figure 4 of tbis species 
wliich corroborates my reading of tbe subject. His figure exbibits 
tbe simple small ears, and tbe sbell without v-strise, but baving some 
1 Dec. II. Yol. I. p. 300, PI. XIII. Figs. 1 and 2. 2 p. 304. 
3 l.c. PI. XIII. Fig. 1 . 4 Figures Cliar. Brit. Foss., vol. i. pl. 39, fig. 3. 
DECADE II. — VOL. IV. — NO. VI. 16 
