200 BuUvSTlN 29 364 



valve very finely crenulate; tooth rugose; free right valve with 

 scales similar to but often longer, more tubular or frondose than 

 those on the left; the two valves are nearly equal in depth, both 

 being moderately convex externally. Altitude 40, greatest width 

 32 mm. 



Gabb referred one of his Dominican Chamas to C. macero- 

 phylla which our party collected on the Monte Cristi beach. It 

 is sub-circular, much more frondose, and not identical with our 

 fossil species. The latter is a trifle like C. Broderipii but smaller. 



Locality. — (Exp'd '16) Zone H, Rio Cana at Caimito. 



Chama congregatoides, n. sp. 

 Plate 33, Figure 8 



Shell heavy, solid, attached by the left valve which is sub- 

 circular in outline, rather deep, convex externally, ornamented 

 with close, irregular, concentric lamellae; beaks deep, turning 

 strongly to the right and forward, very closely appressed to the 

 cardinal region; inner margin of valve finely crenulate. Altitude 

 of shell 31, length 30 mm. 



This species resembles our specimens of the Miocene C. con- 

 gregata Conrad and is of the same general type. 



Locality. — (Exp'd '16) Zone H, Rio Cana at Caimito. 



Chama riocamica, n. sp. 

 Plate 33, Figure 9 



Shell rather thin, triangular in outline; attached by the right 

 valve which is very deep; beak directed forward and to the left, 

 arching over the cardinal area in an Lxogyra-like curve; teeth 

 somewhat rugose and pustulose; inner margin of valve not cren- 

 ulate; outer surface of right valve finely squamose and granulose 

 with a few toothed scales which along the line of attachment form 

 a conspicuous row. Altitude of valve 45, greatest width 30, 

 greatest depth 30 mm. 



This species has the characteristic habit of attaching itself 

 by the right valve and the area of attachment is large. Our 

 other Chamas, — involuta, caimitica, and congregatoides are all af- 



