306 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 45. 



in the ventral valve. On each side of the resiUum, bending outward 

 and downward, is the proviacular area, which in the ventral valve 

 is lightly raised and transversely feebly notched; in the dorsal it is 

 impressed, bearing slender cross bars. Muscular scars very large. 

 Edge of shell outside of palUal line roughened on the dorsal third. 



The type and about 68 loose valves, mostly upper. Cat. No. 246281, 

 U.S.N.M., were dredged at station 5217, in 105 fathoms, off Anima 

 Solalslanddat. 13°20'N.; long. 123° W \b" E.), on coarse gray 

 sand bottom; bottom temperature, 63.1°; density at bottom, 1.02496. 

 The measurements of the type are as follows: Lower valve, altitude 

 11 mm., latitude 12 mm.; diameter at ventral edge 5 mm.; dorsal 

 valve, altitude 9 mm., latitude 10 mm., thickness probably 1 mm. 



DIMYA LIMA, new species. 

 Plate 27; Plate 28, figs. 5 and 6. 



Shell large but much thinner than Dimya JUipina, white with a 

 silvery nacreous suffusion. In adult shells the edge beyond the 

 palHal ridge curves up and lends the shell a dished appearance. 

 Lower valve very thin at the point of attachment, where it is quite 

 translucent; the rest of its exterior, excepting the extreme edge, 

 which is hyaline, is milk white and polished, showing fine, irregular 

 lines of growth. The exterior of the upper valve is almost smooth 

 during the early stages, but sculptured with roughened irregular flake- 

 like squamations (not strong laminations as in. Jilipina), and a few 

 well incised, irregularly spaced, radiating lines on the latter two thirds. 

 Interior bluish white, the edge outside of the pallial line nacreous. 

 Resilium resting in a small pit, which is partly roofed over by a thin 

 shelf, dorsally, in both valves. Radiating outward and downward on 

 each side of the resUiar pit is the provincular area, which appears in 

 both valves as a transversely roughened ridge, fusing ventrally with 

 the considerably thickened pallial border. The latter is crossed by 

 strongly impressed radiating grooves in the upper valve, that corre- 

 spond to an equal number of raised threads in the lower valve. 



The type and many other specimens were dredged at station 5533, 

 off Balicasag Island (lat. 9° 27' 15'' N.; long. 123° 31' 48" E.), in 

 432 fathoms, on green mud and sand bottom; bottom temperature 

 53°.3. All of these were attached to shells of Lima {Callolima) 

 smiihi Bartsch. The type. Cat. No. 256977, U.S.N.M., measures: 

 Altitude 13.5 mm., latitude 15.5 mm. 



Additional specimens were obtained at the following stations : 



On LIMA (CALLOLIMA) SMITHI Bartsch. 



Station 5124, off Point Origon (lat. 12° 52' 00" N.; long. 121° 48' 

 30" E.), in 281 fathoms, on soft green mud bottom. Cat. No. 256978, 



U.S.N.M. 



