dall: mollusca and brachiopoda. 403 



small, polished prodissoconcli) small, pointed, tbe left one rising a little higher 

 than the other ; hinge line straight, ears subequal, sharply pointed, byssal notch 

 and fasciole distinct, sculpture like that of the disk ; surface of the valves with 

 about four easy, wide, rounded undulations ; surface sculptured with numerous 

 fine, squarish, radial and concentric threads subequal and subequally distributed, 

 so that the meshes are mostly square, without nodulation at the intersections, 

 and the interspaces are wider than the threads ; disk short, kite-shaped, a little 

 produced in front, suddenly constricted at the margin ; interior white, polished, 

 the umbonal cavities extending under the hinge line ; the pit and resilium small. 

 Alt. 12.0 ; lat. of shell, 12.0 ; of hinge line, LI ; diam. 4.0 mm. 



U. S. S. " Albatross," station 4721, Pacific Ocean in South Lat. 8° 7', and 

 West Lou. 104° 10', in 2084 fathoms, globigeriua ooze, bottom temperature about 

 35° F. U. S. N. Mus. 110,579. 



This is a most exquisite little gem of the sea. 



Pecten (Pseudamusium) polyleptus Dall, n. ep. 



Plate 10, Oeure 9. 



Shell small, thin, translucent white, compressed, having a marked " Camp- 

 ionedes " striation, beside about thirty-six radial rows of minute, elevated, granule- 

 like scales, very easily detached and more crowded near the middle of the base ; 

 hinge line straight ; anterior ear in the right valve long, prominent, with five 

 radial rows of scales and obvious concentric striation ; byssal notch deep and 

 wide, with a broad fasciole, the ctenolium with three free teeth ; posterior ear not 

 differentiated by a notch ; profile of the valve, below and behind, a segment of 

 a circle ; interior with glassy polish, scar small and high up, hardly visible ; mar- 

 gins entire ; ligameutary pit small, shallow. Alt. of valve, 9.5 ; Ion. of valve, 9.5 ; 

 of hinge line, 6.5 ; diam. of right valve, 1.2 mm. 



U. S. S. "Albatross," station 4642, Galapagos Islands, four miles S., 41° E., 

 from Ripple Point, Hood Island, in 300 fathoms, globigerina sand, bottom tem- 

 perature 48°. 6 F. U. S. N. Mus. 110,586. 



Only the right valve was obtained at this station, but at station 2781, on the 

 west coast of Patagonia, Southern Chile, in South Lat. 51° 52', in 348 fathoms, 

 mud, bottom temperature 50° P., a left valve which probably belongs to the 

 same species was dredged by the " Albatross " in 1888. The sculpture is essen- 

 tially similar, except that the scales are fewer and more distant from each other ; 

 only 34 rows could be counted, and the umbonal part of the valve shows several 

 concentric undulations. The cars are large, subequal, the anterior larger with six 

 radial rows of scales. The " Camptonectes " sculpture is conspicuous upon the 

 glassy shell. 



Pecten (Pseudamusium) gelatinosus Mabille kt Rochebrune. 



Pseudamusium (jilati'nosum M. et R , Mies. Cap Horn, Moll., 1889, 6, p. FI 126. 

 Orange Harbor, Mabille; U. S. S. " Albatross," station 2785, in 449 fathoms, 

 mud, temperature 47° P. U. S. N. Mus. 96,454. 



