CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 55 



with delicate, concentric lines; characters of interior of shell concealed by the 

 matrix. 



Length of shell 24, height 23 mm. 



Remarks. — Gerhardt has described a Protocardia (Protocardium elongatum) 

 from Peru characterized by elongated anterior end and nearly straight hingt line. 

 Gabb also described a species of this genus from Pariatambo, Peru, which like 

 this shell is more triangular, but is characterized by very coarse sculpture. 



The original substance of this shell (which has been entirely removed by 

 solution) was evidently exceedingly thin. This indicates that the conditions 

 under which it lived were quiet and rather deep waters. This harmonizes also 

 with the very fine grained shale in which it is found, — evidently formed some 

 distance off shore and at considerable depths. 



Locality. — On the trail from Parare to Coycuar, about six miles south of 

 Parare, and three miles south of Caituco, in black shales. 



Geological horizon. — Basal Upper Cretaceous? 



Genus MERETRIX Lamarck, 1799. 

 Meretrix cf. nuttalliopsis Heilprin. Plate IX, Figure 8. 



Heilprin's original description. — "Shell sub-elliptical, moderately ventricose, 

 its surface covered with fine concentric striae, which are apt to become roughly 

 imbricate on the basal margin; umbones not very prominent, rather anterior; 

 lunule cordate, deeply impressed at about its middle, its outline clearly pronounced 

 by a sharply impressed line; posterior extremity regularly rounded, the anterior 

 somewhat produced; margin entire; pallial sinus somewhat angular, pointing 

 towards the center of the shell. 



"Length 1>£ inch." 



Lignitic of Alabama, where it is very abundant. 



Remarks. — Among the fossils from Soldado is a Meretrix which resembles in 

 size, form, and concentric sculpture Heilprin's nuttalliopsis; but its state of 

 preservation is too imperfect to admit of positive identification. It is, however, 

 very probably this species or a varietal form. 



Length of fragment 26, height about 25 mm. 



Locality .-—Bed No. 8, Soldado Rock, Gulf of Paria. 



Geological horizon. — Lignitic Eocene. Equivalent to that of Alabama. 



Meretrix subimpressa Conrad. 



Cytherea subimpressa Conrad, Jour. Acad. Nat. Sci. Phila., vol. I, p. 130, pi. 14, fig. 26. 



Conrad 's original description, — "Ovate, slightly ventricose, smooth and pol- 

 ished, with concentric, slightly impressed lines on the anterior side; anterior 

 side short, rather acutely rounded; posterior side produced, acutely rounded at 

 the extremity; dorsal margin long, oblique, slightly curved; beaks prominent; 

 lunule lanceolate, defined by a slightly depressed line. Length lj/£ in. Height 



8 in 



a 



Locality. — Marlbourne, Hannover county, Virginia. Mr. Ruffin. 



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