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II. Leda egregia n. sp. (PI. vii., f. i, 2). 
Lanceolate, narrow, compressed, i\'or5'-shining, inequi- 
lateral, much rostrated posteriori 3-, somewhat rounded 
anteriorl}', with numerous crowded somewhat lamellar con- 
centric ribs, which become almost obsolete on the central 
portion of the valves ; hinge-teeth fine and long, about 30 
in the anterior and 40 in the posterior series, the two series 
separated b3" a broad triangular cartilage pit immediatel}' 
beneath the small and scarcel}^ prominent umbo ; anterior 
dorsal margin gentl}' curv^ed ; posterior dorsal area incurved 
and ver3' distinctly bounded, covered with a dark epidermis, 
and bounded below b}’ a prominent ridge upon which the 
concentric riblets rise into small white points ; another ridge 
runs from the umbo down to the margin to form the lower 
angle of the posterior end. Length 25 — 40 mill., height 
8 — 13 mill. 
Intermediate between N. tellinoides Sow. and N. patagonica 
Orb. Several specimens dredged in the Gulf of Paria b3' 
Mr. W. O. Crosb3\ 
13. Leda patagonica, Orb. 
L. patagonica, D’Orb. V03’. Amer. Mer., p. 544, pi. Ixxxii., 
f. 1—3. 
This fine species in general aspect is not unlike L. lan- 
ceolata and L. egregia. It is distinguished from L. egregia 
by" the flattened, not lamellar, ribs ; it is less rostrated ; the 
dorsal area is not incurved, and is narrower. The other 
differences are not ea.sil3' described, but are readiL" appre- 
ciable upon a comparison of specimens. Our examples are 
larger than D’Orbign5"’s, and measure 49 mill, in length and 
