THE LOWER LIAS OF KEYNSHAM. 
51 
Astarte : 
A. cingulata, Terq. is common in the 0. irregtUarisheds at 
Kelston. ’ 
A. ohsoleta, Dunk. Concentrically marked, fair-sized 
Astarte Sj from the beds just below the Echinid clay, are 
somewhat doubtfully referred to this species. 
A. limbata, Dum. Elegant little Astartes from the 
Calcicosta beds are considered by us to agree with Dumor- 
tier’s description of this species. 
Cardita : 
C. hebcrti, Terq. — Small, finely striate, Card^to-shaped 
lamellibranchs which occur in the Calcicosta beds are unhesi- 
tatingly assigned to this species. 
Pleuromya : 
These fossils occur almost invariably as casts, and but 
seldom show any trace of the characteristic pallial sinus. 
Pleuromya croivcombeia^ Moore. — This very important 
fossil occurs abundantly in the Ostrea beds of Eedland 
and is remarkable for the Panopea-VsikQ character of the 
adult ; the small pointed beaks and the broad, concave 
expansion of the hind part of the valves recall the typical 
Panopeas of the Cretaceous. So far as we know, no figure 
has yet been given of an adult, but the young form is figured 
satisfactorily in Tate and Blake’s Yorkshire Lias. 
Pleuromya {Grossly a) galathea, Ag.— This is a very 
common and important fossil of the 0. irregularis beds. It 
possesses the Gresslya-\\kQ characters of form and lunule, 
but the deep groove, seen in the type of the genus 
{G. abducta), is. seldom, if ever, conspicuous. 
Pleuromya liasina^ Schubl.^ — To this species are re- 
ferred the numerous casts which have the beaks facing each 
other and not placed very near to the anterior. Our speci- 
mens do not, however, in all respects, agree with the type, 
