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44 CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 



gence of the west coast species from a common stock in the Antilles from which 

 it migrated westward before the rise of the isthmus. 



The short, high type of Noetias of which A. sheldoniana is an example is 

 found in the Oligocene beds of the east coast but apparently at the close of that 

 period it died out in the Antilles. On the west coast it continued to develop 

 to the present time where the type is represented by Area (Noetia) reversa. 



Area trinitaria 1 * described by Dr. Guppy from the Manzanilla beds of 

 Trinidad (which Dall and Guppy in 1896 called probably Eocene but which Dr. 

 Dall later thought to be Oligocene) is of the same short high type of Noetia. 

 It also died out. Although evidently a near relative of that species A. sheldoni- 

 ana is not nearly so produced posteriorly and is specifically distinct. 



Locality.— Along the shore 1000 feet west of Brighton Pier, Trinidad Island, 

 in a black asphaltic marl. 



Geological horizon. — Approximately equivalent to the Chipola (Upper Oligo- 

 cene) epoch of Florida. 



This shell is dedicated to Miss Pearl Sheldon, of the Geological Department of 

 Cornell University, who has just completed a monograph on the genus Area and 

 to whom the writer is indebted for help in the differentiation of this species. 



Area (Cunearca) chemnitzioides new species. Plate VII, Figures 13, 14, 15; Plate VIII, Figure 1. 



Description.— Shell trigonal, short and high with prominent and widely sepa- 

 rated beaks; cardinal area diamond-shaped with transverse striations and with- 

 out V-shaped grooves; this and the general form show it belongs to the section 

 Cunearca. Nearly all the specimens are in the form of internal moulds, but 

 several were casts of the exterior and gutta-percha impressions of these show the 

 ribs were beaded as indicated in the figure. 



Length of an averaged sized mould 22; height 21; diameter 16.5 mm. 



Remarks.— Judging from these characters the shell might be taken to be Area 

 (Cunearca) cumanensis Dall 14 from the Oligocene of Cumana,|Venezuela, and from 

 an island in Lake Henriquillo, St. Domingo. This species has never been figured 

 but it is so like Area incongrua Say 16 that Dr. Guppy referred it to that species in 

 his list of the Tertiary shells of the West Indies 16 and Dr. Dall in describing 

 cumanensis says it resembles incongrua closely, although the valve is shorter and 

 higher. The high narrow beaks and wide cardinal area separate the Trinidad 

 fossil from incongrua. And its general aspect is so unlike that species that it 

 could hardly be cumanensis which Dr. Dall says is like incongrua in miniature. 



But the Trinidad shell recalls at once Area chemnitzii Philippi of the recent 



east coast fauna, and also an ancestral form of that species Area alcima Dall 17 



from the Pliocene of Florida. A gutta-percha mould of a specimen of A . chemnitzii 



18 Proc. Geol. Soc. London, vol. 22, p. 583, pi. XXVI, fig. 3a, 3b, 1866. 

 14 Trans. Wagner Inst. Sci., Ill, pp. 633-634. 



16 Jour. Acad. Nat. Sci. Phila., II, p. 268, 1822. 

 14 Geol. Mag., 1874, p. 451. 



17 Trans. Wagner Inst. Sci., Ill, pp. 635-636. 



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