148 EOCENE MOLLUSCA. 
Shell orbicular, slightly oblique, not very thick ; tumid, heart-shaped, inequilateral ; 
costated, ribs 23—26, convex and smooth on the centre of the shell, slightly granular on 
each side, particularly those in the pedal region. 
Diameter + an inch. 
Localities. Bracklesham, Selsey, Brook ( Hdwards). 
In Mr. Dixon’s work, and also in Mr. Morris’s ‘ Catalogue of Brit. Fossils,’ is the name 
of C. mitis. The specimen from which our figure is taken has likewise the same name in 
MS., and I have therefore here retained it, although it does not fully accord with the 
description of the French species of that name. M. Deshayes considered his shell entitled 
to be separated from C. planicosta (the young of which it much resembles), principally on 
account of the difference in number of costee, which in mz/zs are said to be as many as 
thirty-nine, while in planicosta there are not more than thirty, and this latter number is 
the full extent of what our shell possesses. Still, I think our British fossil is not the 
young of planicosta, as it differs in outward form in being more orbicular, more tumid, 
and less oblique, and the ribs in p/anicosta are flatter even in the young shell than they 
are in our present species. In this shell the cost in the pedal region are covered with 
obtuse tubercles or nodules, and the ribs are not wider than the interspaces. 
11. Carpita osovata, Edwards, MS. Tab. XXII, fig. 138. 
Spec. Char. C. Testa transversd, elongaté, oblonga vel subquadrangulari; valdé 
mnmequilateralt, radiatim costatd, costis numerosis depressis, subplanatis ; umbonibus obli- 
quis, depressis ; lunuld parva, cordiformi ; cardine crassiusculo. 
Shell transverse, elongate, oblong or irregularly quadrangular, very inequilateral ; cos- 
tated ribs numerous, somewhat depressed; lunule small concave, heart-shaped; hinge 
moderately thick. 
Length, Zths of an inch; height, $ths of an inch. 
Locality. Bracklesham. 
‘'wo specimens are in Mr. Edwards’s cabinet, to which he has given the above name, 
and I have provisionally adopted the separation he has made. ‘The form of the shell is 
different from that of any other except carinata, to which it may, perhaps, be referred as a 
variety ; but our present species has a greater number of ribs (thirty), whereas in carinata 
there are only twenty-two. In this the coste are not so angular, and they are more 
nodulous, 
