349 Dominican Fossils — Maury 185 



Shell suborbicular, very inequivalve, with about twenty radi- 

 ating, sharp ribs, each distinctly medially grooved, separated 

 by deep V-shaped interspaces; ears small, unequal; inner margin 

 of shell deeply fluted ; right valve very convex, left much com- 

 pressed, nearly flat; with one or both edges of the ribs beauti- 

 fully squamose. Length of a right valve 26, altitude 26, semi- 

 diameter 8; corresponding measures of a left valve 23X23X4 

 mm. The type was described only from a right valve. We 

 have ten left valves, — the first ever found. The edges of the ribs 

 of the right valves are smooth when worn, as in the type, but on 

 fresher shells they appear to be squamose as on the left valves. 



Dr. Dall very kindly compared our shells with his type. 



Localities. — (Exp'd '16) Samba Hills at an altitude of ap- 

 proximately 540 feet (common). Zones B, F, Rio Gurabo at 

 Los Quemados; trail Hato Viejo to Potrero, Rio Amina. 



Pecten (sEqtiipecten) Thetidis Sowerby 

 Plate 34, Figure 6 



Pecten Thetidis Sowerby, Quart. Jour. Geol. Soc. London, vol. 6, 



p. 52. 1849. 

 Pecten thetidis Gabb, Trans. Amer. Phil. Soc., vol. 15, p. 256, 1873. 

 Pecten thetidis Guppy, Quart. Jour. Geol. Soc. London, vol. 32, p. 



532, 1876. 

 Pecten {JEquipecten) thetidis Dall, Trans. Wagner Inst. Sci., vol. 3, 



pt. 4, p. 714, 1898; pt. 6, p. 1586, 1903. 



The type of this unfigured species was collected by Heneken 

 in the Yaqui Valley. We are indebted to Dr. Dall for compar- 

 ing our shells with his shells from Bowden which in turn were 

 compared with Sowerby's type. The shell is orbicular, with 

 typically nineteen square ribs each with rows of minute spiny 

 squames; interstices in older shells also squamose; ears unequal, 

 with squamose radiating threads. Our largest specimen is 33 

 mm. in altitude, a small perfect shell measures 17X17, semidiam- 

 eter 4.25 mm. The species is also found at Bowden and on Cur- 

 acao. 



Localities. — (Exp'd '16) Zone I, Rio Cana at Caimito; 

 Samba Hills at approximately 540 feet altitude. 



