. 



CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 45 



collected by Mr. Schultz in a sandy cave south of Brighton on the Gulf of Paria 

 is almost exactly the shape of the moulds of the fossil shells. But some of the 

 latter appear to have been of considerably larger size than the recent forms 

 attains. 



Locality. — Southern main road just south of Pitch Lake, Brighton, Trinidad 

 Island, in a reddish-yellow, highly ferruginous marl. Lithologically the forma- 

 tion is very like that of the Lignitic Eocene at Many, Louisiana. 



Geological horizon. — Areas of this type characterized by high umbones and 

 short high form of shell are not known below the Oligocene on the southeastern 

 coast of the southern United States and the Antillean area. Hence short, high 

 Areas mean Oligocene or later. Such types have been found in beds called 

 Eocene but which proved later to be really Oligocene. An instance of this is 

 Area filicata Guppy, a form related to the species described above, from the 

 Manzanilla beds of Trinidad. These were first thought to be Lower Miocene 18 

 then Eocene, 19 then Oligocene. 20 From these indications the bed with ferruginous 

 casts would appear to be Oligocene or later. 



Area (Argina) billingsiana new species. Plate VIII, Figures 2, 3. 



Description. — Shell transversely oval-elongate, rather thick and strong, beaks 

 nearly touching, incurved over the narrow cardinal area which is similar to that 

 of Area campechensis Dillwyn, ribs of the left valve generally simple, sometimes 

 faintly grooved, about 29 in number. 



Length of shell 31; height 22, thickness of one valve 10 mm. 



Remarks. — This species recalls the outlines of members of Scapharca (Scaph- 

 arca) transversa Say 21 group; but the hinge shows the characters of Gray's section 

 Argina (1840) of the subgenus Scapharca. In Argina the hinge teeth are in two 

 series, — the anterior shorter, more or less irregular and broken, and the posterior 

 longer, normal. 



The only members of Argina described from the Tertiaries of the Gulf or the 

 Antilles are (1) Scapharca (Argina) tolepia Dall 22 from the Oligocene of Rio Amina, 

 Santo Domingo; Bowden, Jamaica; and Cumana, Venezuela, and (2) Scapharca 

 (Argina) campechensis Dillwyn 23 from both of which the Trinidad shell is specifi- 

 cally distinct. 



The Cumana shell, A. topelia was referred by Dr. Guppy in his list of the 

 West Indian Tertiary shells 24 to Area pexata Say; but it can be distinguished by its 

 remarkable inflation, its diameter being practically equal to its length. 



A recent species of Argina was collected by Mr. Alfred Schultz in a sandy cove 



18 Guppy, 1866. 



19 Guppy 1874, Guppy and Dall 1896, Dall 1898. 



20 Dall and others. 



21 Jour. Acad. Nat. Sci. Phila., 1st ser., II, p. 169, 1822. 



22 Trans. Wagner Inst. Sci., Ill, pp. 649-650, pi. 33, figs. 7, 8, 1898. 



23 Descr. Cat. Rec. Shells, I, p. 238, 1817. 



24 Geol. Mag., London, 1874. 



