MUSEUM OF COMPARATIVE ZOOLOGY. 297 
present one. Had Miss Bush in her excellent paper had more material, she 
would probably have hesitated to give a name to the pretty species she has 
called costata. Her distinctions from ornatissima are that the ribs are less 
numerous, more curved, and the shell less convex in the Carolina specimens. 
I find in her figure eight visible ribs; in seven valves from the Carolina coast 
I find the ribs varying from five to seventeen; the strong ones extending to the 
beaks number from five to eight; their curvature varies somewhat. The di- 
ameter of D’Orbigny’s figure relative to its height is as 11:14, while in Miss 
Bush’s specimens it is, she states, as 4:4,so that her specimens were really 
more convex than D’Orbigny’s, rather than less so. But his figures, made in 
1840 or so, and much magnified, must not be construed too literally, as they 
are on the face of them a little formal, though excellent for the time. 
Cardiomya costellata Desuares. 
Corbula costellata Desh. Expl. Sci. Morea, Géol., p. 86, pl. vii. figs. 1-8, 1837. 
Neera costellata Jeffreys, Brit. Conch., III. p.49; V.p. 191, pl. xlix. fig. 3; P.Z.S, 
1881, p. 944. 
Necra curta Jeffreys (name, no description), Valorous Moll., Ann. Nat. Hist., 1876, 
p. 495; P. Z. S., 1881, p. 943, pl. Ixxi. fig. 10. 
Sphena alternata D’Orbigny, Moll. Cuba, II. p. 286, 1846; Atlas, pl. xxvii. figs. 
17-20, 1845. 
2 Neera alternata (D’Orbigny) Dall, Bull. M. C. Z., IX. p. 110, 1881. 
A fine series of specimens in the Jeffreys collection, especially from the 
Mediterranean, is sufficient to convince the most sceptical of the great vari- 
ability of this species. It varies from smooth, or with but two or three radi- 
ating coste, to completely radiated all over; the rostrum varies in actual and 
in relative length and direction; the amount of inflation, its direction, and 
consequently the outline of the shell, vary considerably. The European speci- 
mens sometimes have a smooth interval between the end of the rostrum and 
the radiating sculpture of the body, and sometimes the whole is covered with 
radii, The most common form seems to be that in which there are compara- 
tively few and rather strong radii on the posterior part of the shell, with the 
rest smooth or faintly radiated, and the rostrum smooth, except a few radii on 
its dorsal side, and rather long, This form has been collected by Hemphill in 
two fathoms at Marco, Florida, and has been dredged by the U. S. Fish Com- 
mission at Stations 2597, 2602, and 2614, off the Carolina coast. These are all 
small, Jeffreys’ finest British specimens being about 10 mm. long, and the 
average length of those from all localities being about 6-7 mm. The form 
named curta by Jeffreys (which may rank as a variety though connected by 
indefinite gradations with the type) is also small, and has the rostrum short 
and recurved, the striation strongest posteriorly but varying, as in the type. 
Some of the specimens dredged by the U. S. Fish Commission at Station 2602 
were of this variety. 
