PALEONTOLOGIC CONTRIBUTIONS 7 1 



Orbiculoidea molina nov. 

 Plate 24, figures 1-4 



Description. Valves small, subcircular, fiat. Apex of pedicle 

 valve at center or anteriorly (to one-fourth of radius) of it, little 

 prominent; surface sloping fairly uniformly to all sides, though in 

 most specimens through pressure the valve has been flattened and 

 the apex forms a small prominent knob, projected forward. The 

 pedicle slit extends from apex to margin, is depressed and marked 

 with radial lines, when seen from the outside ; from the inside it 

 appears as a fusiform semiconical prominence. The brachial valve 

 (probably larger) has the same outline and elevation as the lower 

 valve ; the apex is in most specimens somewhat nearer to the 

 anterior margin. The surface shows fine concentric growth-lines 

 which toward the margin become increasingly lamellose, coarser 

 and irregular in size. 



Measurements. Largest diameter of brachial valve observed, 

 J.J mm; of a pedicle valve, J mm in longitudinal direction and 

 6 mm transversely. 



Horizon and locality. Lowest Bertie waterlime (probably of 

 Pittsford age) at Farmer's Mills near Utica, in association with 

 Lingula alta and Eusarcus vaningeni. 



Remarks. . While this small orbiculoid brachiopod has been 

 found only in the horizon with Eusarcus vaningeni at 

 Farmer's Mills, it is there as abundant as the Lingula ; there were 

 counted seven specimens in the space of a square inch. On the 

 same slab in the space of a square foot remains of three Eusarci 

 were scattered. 



Hall described as O . vanuxemi a form from the " Water- 

 lime group " which may have come from the Bertie waterlime, 

 but more probably is derived from the Manlius limestone or another 

 formation of the Helderberg group. At any rate our species differs 

 from it in its smaller size and relatively smaller elevation and the 

 lack of the radiating lines. It is, however, quite similar to O . 

 n u m u 1 u s Hall and Clarke, a Manlius type, in outline and eleva- 

 tion. The latter form differs in being larger, having coarser striae 

 and a deeper and shorter pedicle groove in the exterior aspect. 



The writer has also seen in the Museum of the Buffalo Society of 

 Natural Sciences a large Orbiculoidea, from the Bertie waterlime, 

 as yet undescribed but already cited in several fossil lists as 

 Orbiculoidea sp. 



