246 BULLETIN OF THE 
A. With smooth margin. 
Nucula egeénsis (Forzes) Jerrreys. 
Nucula tenuis Montagu, Dall, Bull. M. C. Z., IX. p. 128. 
Nucula egeénsis Jeffreys, P. Z. S., 1879, p. 581. 
Habitat. Sigsbee, off Havana, 175 and 450 fms.; off Morro Light, 292 
fms.; Station 20, 220 fms.; Station 3, 450 fms.; and Station 230, near St. 
Vincent, in 464 fms.; all mostly dead valves. 
In examining specimens dredged off the Carolinas by the Fish Commission, 
I was struck by the fact that only N. proxima and not a single N. tenuis had 
been secured. This led me to review the specimens identified for me by Dr. 
Jeffreys as N. tenuis, and so named in the preliminary report, as above. I 
have compared them with all the varieties of tenuis, and with all the specimens 
of egeénsis in the Jeffreys collection. The Blake specimens, nearly all being 
separated valves, agree in form and general appearance with the flatter forms 
of tenuis, the only external differences being that the former are a little more 
pointed and pinched dorsally behind, and that two moderately distinct ridges 
enclose a very narrow elongated area along the upper posterior margin. 
Symptoms of such an area were visible occasionally in individuals of genuine 
tenuis, but not so clearly defined. Inside, the hinge line of tenuis is narrower, 
the teeth more delicate and perhaps fewer, the cartilage pit a little smaller. 
These are just the differences which separate tenuis from N. egeénsis, and it is 
probable that the Blake specimens should be referred to the latter species. It 
is by no means clear to me that @geénsis is anything more than a geographical 
race of tenuis; but so far, though the hinge characters are slight, I have not 
found many intermediate specimens. The West Indian specimens are larger 
than those from the Mediterranean, and consequently the number of teeth is 
greater, but the proportion is about the same in all. The largest specimen 
measures 10.7 max. lon., 8,0 max. alt., and 4.7 mm. max. diam., with 8 anterior 
and 15 posterior teeth. 
Nucula cymella, n. s. 
Shell small, white, rather thick, rounded, triangular, moderately convex; 
beaks somewhat anterior, not prominent; exterior sculptured with evenly 
distributed concentric waves or narrow lire separated by wider interspaces; 
an obscure flexuosity in front of the beaks indicates, without sharply defin- 
ing, a lunule over which the concentric sculpture passes; a faint ridge ex- 
tends backward from the beaks half as far as the teeth, but becomes obsolete 
without enclosing an area; inside, the shell is brightly pearly, the margin 
plain, with seven anterior and eight or nine posterior rather stout teeth, sepa- 
rated by a good-sized cartilage pit, directed vertically downward from the 
