BIVALVIA. 117 



15. Nucula proava, S. Wood. Tab. XX, fig. 3, a, b. 



Spec. Char. N. testa transversa, ovato- oblong a, turgiduld, laevigata, valde inaquilaterali ; 

 untbonibus minimis, terminalibus ; lunula nulla; ano brevi, ovato, in medio prominulo ; 

 margine dorsali convexiuscitld ; margine ventrali curvatd ; dentibus ad apicem gradatim 

 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 ; height, \ an inch. 



Locality. Near Bishopstone, Heme 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 N. lavigata 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 N. Bowerbanhii, 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. Nucula protracta, Edwards, MS. Tab. XVIII, fig. 15. 



Spec. Char. N. testa transversa, elongato-ovatd, laevigata, tenui, tumidiusculd, valde 

 inaquilaterati ; pedi-regione ovato-subattenuatd ; siphoni-regioni brevi, oblique truncatd vel 

 angulatd ; lunula parvd, lanceolatd, unisulcatd ; ano ovato, vix conspicuo ; marginibus 

 crenidatis. 



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, |ths of an inch ; height, T 9 5 ths of an inch. 



Locality. Bracklesham {Edwards). 



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 



