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11. Leda egregia n. sp. (PL vii., f. 1, 2). 



Lanceolate, narrow, compressed, ivory-shining, inequi- 

 lateral, much rostrated posteriori y, somewhat rounded 

 anteriorly, 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 by a broad triangular cartilage pit immediately 

 beneath the small and scarcely prominent umbo ; anterior 

 dorsal margin gently curved ; posterior dorsal area incurved 

 and very distinctly bounded, covered with a dark epidermis, 

 and bounded below by 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 hy 

 Mr. W. O. Crosby. 



13. Leda patagonica, Orb. 



L. patagonica, D'Orb. Voy. Amer. Mer., p. 544, pi. lxxxii., 

 f. i-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 easily described, but are readily appre- 

 ciable upon a comparison of specimens. Our examples are 

 larger than B'Orbigny's, and measure 49 mill, in length and 



