ORTMANN : TERTIARY INVERTEBRATES. 83 



Fam. LEDID^. Ad. 



Gen. LEDA Schum. 



24. LEDA OXYRHYNCHA (Philippi). 



PI. XXVI, Fig. 2"'*. 



1887 Nucula ox. Philippi, Tert. Quart. Verstein. Chiles, p. 197, pi. 41, f. 21. 

 1900 Leda ox. Ortmann, in: Amer. Journ. Sci., v. 10, p. 378. 



Shell elongate, anterior end shorter, rounded, posterior produced and 

 acutely rostrate. Posterior dorsal margin slightly concave, ventral margin 

 evenly arcuate. An angular ridge runs from the apex to the posterior 

 end, and, below this ridge, there is a slight depression. Surface of shell 

 with concentric ribs, between which fine radiating striae are present, which 

 do not cross the ribs. The part of the shell between the posterior dorsal 

 margin and the radial ridge running to the posterior end (escutcheon) has 

 more numerous and finer concentric ribs. Anterior hinge teeth ca. 12, 

 posterior ca. 19. 



Length, 10 mm; height, 6 mm. 



Remarks: The individuals from Santa Cruz are a little shorter than the 

 figure given by Philippi, and the apex is a little more anterior. Of the 

 casts from Arroyo Gio only one is large (length, 12 mm; height, 6 mm), 

 and here the form and situation of the apex agree with Philippi's figure. 

 An external cast from the same locality shows the characteristic sculpture 

 of this species. 



The radial striae, between the concentric ribs, are distinct only near the 

 ventral margin ; toward the apex they are indistinct or even wanting. 

 The original discription of Philippi does not give the details of sculpture 

 mentioned above, so that there remains some doubt as to the identity of 

 our form with the Chilian; I have made the identification chiefly on the 

 ground of the agreement in the general appearance, and because none of 

 the characters given by Philippi contradicts it. 



Record of specimens : Mouth of Santa Cruz River, 2 right, 2 left valves; 

 Arroyo Gio, 6 casts. 



Distribution: Navidad beds of Chili ; Lota, Lebu, Navidad (Phil.). 



Affinities: An allied form is known from New Zealand ("juengere Ab- 

 teilung" = Pareora or Miocene), and figured but not named by Zittel 



