894 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



MONTACUTA MINUSCULA Ball. 



Montacuta minuscula, new species. 



(Plate LXXXVIII, fig. 8.) 



A. 29. Shell small, very thin, white, brilliantly polished; inequilat- 

 eral, with the posterior end shorter, rounded, the anterior wider and 

 obtusely pointed; the dorsal margin before the beaks convexly arcuate; 

 lamellai obsolete in the left valve; valves with the beaks low, the sur- 

 face with faint incremental sculpture; adductor scars elongate, narrow, 

 the anterior not well distinguishable from the pailial line. Lon. 2.7, 

 alt. 1.7, diam. 1.1 mm. 



A single left valve was dredged by the U. S. Fish Commission, o6 

 miles south i] west from Cape Hatteras in 124 fathoms, sand, bottom 

 temi^erature Gl°. 



MONTACUTA LIMPIDA Dall. 



Montacuta limpida, new species. 



(Plato LXXXVIl, figs. 5, 11.) 



A. 30. Shell small, thin, white, inflated, uniformly ovate; beaks 

 small, low, but very distinct; surface concentrically minutely striate, 

 the striae stronger at regular intervals, no radial sculpture; the mar 

 gin forms an uninterrupted oval; the right anterior lamella is present 

 but feeble and its hook or cardinal though visible is somewhat obsolete; 

 the adductor scars are narrow, the pailial scar linear. Lon. 3, alt. 2.5, 

 diam. 1.8 mm. 



An apparently young right valve was obtained in 294 fathoms, coral 

 sand, off Fernandina, Florida, bottom temperature 40.3° F. ; an adult 

 valve supposed to be conspecific and which has been selected as the 

 type came from a depth of 85 fathoms, 5 miles off Cape Florida, in 

 the Gulf of Mexico. The younger valve has a length of l.G mm.; is 

 slightly more pointed behind; has the dental hook proportionately 

 more prominent, and the pailial line wider and less distinguished from 

 the adductor scars. 



MONTACUTA PERCOMPRESSA Dall. 



Montacuta percompressa, new species. 



A. 31. Shell small, thin, compressed, oblong-ovate, white^ tinged with 

 reddish brown near the umbones; inequilateral; the posterior side 

 shorter, bluntly rounded; anterior side produced, narrower; beaks 

 depressed; surface ratlier irregularly concentrically striated and some- 

 times feebly waved; lamelhe feeble, almost obsolete; adductor scars 

 narrow, rather irregularly merging in the somewhat ragged pailial line. 

 Lon. 3.7, alt. 2.9, diam. 1.4 mm. 



