192 Bulletin 29 35^ 



Genus Placunanomia Broderip 



Placunanoviia lithobleta Dall 



Plate 34, Figures i, 2 

 Placunanomia lithobleta Dall, Trans. Wagner Inst. Sci., vol. 3, pt. 4, 

 p. 778, 1898; pt. 6, p. 1586, 1903. 



We collected several specimens which accord with the de- 

 scription of this rare, unfigured species described from the Bow- 

 den beds, Jamaica. Our perfect shell measures 45 mm. in 

 length, |and 45 in altitude, but we have fragments of much larger 

 shells. The surface is marked by fine, wavy, radial threads, 

 minutely knotted or postulose; interior nacreous. This genus is 

 now reported for the first time from Santo Domingo. 



Locality. — (Exp'd '16) Guayubin to Mao road, Rio Cana. 



Genus Modiolus Lamarck 

 Modiolus cercadicus, n. sp. 

 Plate 26, Figure 16 



Shell minute, thin, fragile, translucent, with about eighteen 

 flat, strong, slightly nodular ribs, not divaricating and with much 

 narrower, linear, interspaces. The ribs do not extend over the 

 anterior portion of the valve which is smooth and marked by a 

 broad, pronounced sulcus. Greatest length 5, greatest width 4 

 mm. 



Gabb mentions finding two minute specimens of Modiolus 

 which may have been this species. We have half a dozen valves 

 all about the same size. It is very likely immature but is well 

 characterized by the strong sculpture. M. Gtippyi Dall from 

 Bowden is also small, measuring 9 mm. in length, but with more 

 numerous ribs and characteristically feeble sculpture and the shell 

 is not anteriorly sulcate. 



Locality.— (Exp'd '16) Bluff 3, Cercado de Mao. 



Modiolus maonis, n. sp. 

 Plate 26, Figure 17 

 Shell very thin, translucent, perfectly smooth except for del- 



