BIVALVIA. W7 
15. Nucuna proava, 8. Wood. Tab. XX, fig. 3, a, 6d. 
Spec. Char. N. testa transversd, ovato-oblongd, turgiduld, levigatd, valde inequilateral ; 
umbonibus minimis, terminalibus; lunuld nulld ; ano brevi, ovato, in medio prominulo ; 
margine dorsali convexiusculd ; margine ventrali curvatd ; dentibus ad apicem gradatin 
minutissimis ; marginibus integris. 
Shell transverse, ovately oblong, slightly tumid, smooth, and very inequilateral ; beaks 
small, depressed, terminal; no lunule ; anal region short, distinct, and slightly prominent 
in the centre; dorsal and ventral margins slightly curved, the latter rather the more so ; 
teeth not very close, diminishing towards the umbo; margins smooth. 
Length, ths of an inch; eight, } an inch. 
Locality. Near Bishopstone, Herne Bay. 
A single specimen of this species is in the Museum in Jermyn Street, and the officers 
of that establishment have kindly permitted me to have it figured. It is the only one 
that I have seen. 
The nearest approach to this shell that I know is WV. /evigata of the Coralline Crag, 
but it differs from that species in outline; it is less curved in the ventral margin, and the 
anal region is shorter. In form it somewhat resembles V. Bowerdankiz, but that species 
has the inner margins crenulated. The denticles are not very numerous on the pedal 
side; they are hidden by the matrix on the margin of the anal region ; so, also, is the 
place for connexus. 
16. Nucuta prorracta, Adwards, MS. ‘Tab. XVIII, fig. 15. 
Spec. Char. N. testa transversd, elongato-ovatd, levigatd, tenur, tumidiusculd, valdé 
inaquilaterali ; pedi-regione ovato-subattenuatd ; siphoni-regioni brevi, oblique truncata vel 
angulata ; lunuld parva, lanceolatd, unisuleatd ; ano ovato, vir conspicuo ; marginibus 
crenulatis. 
Shell transverse, elongately oval, smooth, thin, slightly tumid, and very inequilateral ; 
pedal region obtusely pointed ; siphonal region short, obliquely truncated or angulated ; 
lunule small, plain, elongated, and flat; corselet ill-defined ; margins crenulated. 
Length, iths of an inch; height, &ths of an inch. 
Locality. Bracklesham (//dwards). : 
A single specimen in Mr. Edwards’s cabinet, from which the figure above referred to 
was taken, appears to be distinct, and I have, in consequence, adopted the MS. name 
