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62 CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 



Locality. — Along the shore 1000 feet west of the Brighton pier, Trinidad, in 

 an impure asphalt. 



Geological horizon. — Upper Oligoeene, about equivalent to the Chipola marls 

 of Florida. 



Genus CORBULA Bruguiere, 1792. 



Corbula (Cuneocorbula) helenae new species. Plate IX, Figure 25. 



Description. — Shell small, sub-equilateral, nearly equivalve; general form ob- 

 long-ovate, posterior slope carinate, posterior end truncate, anterior end broadly 

 rounded; beaks low, approximate; concentric sculpture on both valves of numer- 

 ous, close-set, more or less obsolete and feeble ribs; radial sculpture, especially 

 on the left valve, of very fine, close striae radiating from the beaks to the lower 

 margin, most strongly developed near the carina. 



Length 8, height 5, diameter 3 mm. 



Remarks. — In general outline this shell is nearest to Corbula (Cuneocorbula) 

 sarda Dall from the Chipola Oligoeene of Florida, but C. helence is a shorter 

 and more delicate shell. 



The radiating striae in C. helence are unusual in the genus, but occur in some 

 species as C. (Cuneocorbula) sericea Dall from the Bowden Oligoeene of Jamaica 

 and in C. lavalleana Orbigny, of the recent Antillean fauna. 



This shell is named in honor of Mrs. Alfred Schultz, of Washington, D. C. 



Locality. — Along the shore at Brighton, Trinidad, 1000 feet west of the pier, 

 in an impure asphalt. 



Geological horizon. — Upper Oligoeene, about equivalent to the Chipola horizon 

 of Florida. 



Corbula (Cuneocorbula) subengonata Dall. Plate IX, Figure 24. 



Corbula engonata Aldrich, Bull. I, Geol. Surv. Alabama, p. 58, 1886. Not of Conrad, Proc. 



Acad. Nat. Sci. Phila., Ill, p. 294, 1848. 

 Corbula alabamiensis Lea var., Harris, Bull. Am. Pal., vol. II, p. 260, pi. 13, fig. 14, a, 1897. ' 

 Corbula subengonata Dall, Trans. Wagner Inst. Sci., vol. Ill, p. 841, 1898. 

 Corbula subengonata Clark and Martin, Eocene, Maryland Geol. Surv., p. 163, pi. XXXII, figs 1., 



a, 2, a, 1901. 



Harris' description. — "This variety is by no means so large nor so inflated 

 as alabamiensis, yet some specimens seem to indicate a transitional stage so far 

 as form is concerned. From Corbula engonata this is distinguished by its more 

 compressed form, smaller concentric lines and more rectilinear base" (1897). 

 Type locality, Gregg's Landing, Alabama. Lignitic Eocene. 



DalVs description. — "This form is smaller, less inflated, thinner, and with 

 more nearly parallel dorsal and ventral borders than C. alabamiensis. The 

 sculpture is finer than in C. engonata; which is a more elongated species" (1898). 



Remarks. — On comparing one of our two species of Corbula from Bed No. 8, 

 Soldado Rock, with a specimen of engonata from Gregg's Landing, the shells 

 are found to match perfectly in size and shape. The only difference is that the 

 concentric grooving is somewhat more distant, bolder, and coarser in the Soldado 

 form. 



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