DESCRIPTION OF SHELLS. 165 
pressed, surface much undulated concentrically ; extremities rounded, almost 
closed; beaks slightly prominent, blunt, near the anterior extremity: length 5, 
height 3. 
Whether this be a species or only a variety of P. intermedia, Tab. I. f. 2, 
altered in form by living in clay or mud, not clear sand, may be a question ; it is 
abundant at Bracklesham in the sandy clay ; and it is also found near Bognor in 
clay, while the P. intermedia is in the sandstone. The position of the beaks, 
nearer the anterior side than in P. intermedia, might at first be taken for a di- 
stinguishing character, but it is not constant. 
Cardilia leviuscula. (Tab. II. fig. 6°.) 
Spec. Cuar.—Obovate, ventricose, almost globose, smooth, with a few irre- 
gular furrows on the posterior portion, and many fine elevated lines radiating 
from the beaks ; lines of growth conspicuous. 
A very curious little shell belonging to a remarkable genus instituted by 
Deshayes, and of which only two other species are known, one recent and one 
fossil. The internal plate or septum, by which it is at once recognised, only 
occurs in one other genus, Cucullea, of a totally different form and structure. 
The spoon-shaped pit for the internal ligament, and the equal valves point out 
that it belongs to the family of Mactracea. 
Mr. F. E. Edwards is the fortunate discoverer and possessor of this rarity. 
Corbula costata. 
The shell named C. revoluta in ‘ Mineral Conchology ’ not being that species, 
we are under the necessity of giving it a new name; it is one of the few shells 
which occur at Bracklesham as well as Barton, and like several other shells 
which are found at both places, it is common at Barton but rare at Bracklesham. 
Psammobia compressa. 
Specimens in the Collection of Mr. Edwards, who has been very successful in 
clearing out his fossils, have the hinges perfect, and show that this is not a 
Sanguinolaria as it was formerly supposed to be. 
Tellina donacialis. (Tab. Ill. figs. 8 & 9.) 
The two shells figured differ so much in outline, that they may not be thought 
Z 
