THE LOWEE LIAS OF KEYHSHAM, 
49 
found specimens attached to Lima gigantea from the upper 
Psilonotus beds at Keynsham and Redland and others from 
the Bisulcatiis zone. 
Lima : 
L. valoniensiSj de France. {L. punctata^ Auct) charac- 
terizes the Ostrea liassica beds. All the specimens we 
have seen are easily separated from L. punctata^ which 
is a mere mutation of L. gigantea. 
L. hermanni^ Voltz. may be taken to include L. succincta^ 
Schloth. 
L. gigantea^ Sow. may be taken to include L. punctata.^ Sow. 
L. hettangiensis^ Terq. is a very important stratigraphical 
fossil ; specimens are abundant and, when full grown, agree 
exactly with the figure and description given by Terquem. 
When the duplicate character is not developed until late, and 
when the interspaces are, at the same time, broader than 
usual, the species approaches very close to L. pectinoides., Sow. 
This species is usually named L. pectinoides, and we are 
not yet convinced that either of the two specimens in the 
Sowerby collection, labelled L. pectinoides^ is distinct from 
the young of L. hettangiensis. 
L. stigma^ Dum. A single specimen from the Bisulcatus 
beds is somewhat doubtfully referred to this species. 
Pecfen : 
The group of smooth Pectens may be tentatively included 
in P. calvits^ Goldf . but a more detailed study of their charac- 
ters and more accurate observations on their occurrence in the 
rocks are needed before their mutual relationship can be 
considered to be definitely settled. 
Smaller forms of very similar character occur in the 
Psilonotus zone, but the larger forms are most abundant in 
the Angulatus beds. 
P. textoriuSj Schloth. occurs in its most typical form. 
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