250 REPORT ON ALBATROSS MOLLUSCA — DALL. 



Section P8EUDAMUSIUM H. & A. Adams. 

 Pecten (Pseudamusium) strigillatum Dall. 

 Plate xi, Fig. 2. 

 Psevdamusium strigillatum Dall, Bull. Mas. Comp. Zoo!., xviii, p, 433, June, 1889. 



Shell small, white, thiu, rounded, with a straight hinge-margin ; left 

 valve inflated, the posterior auricle narrow, separated by a deep nar- 

 row byssal notch from the rest of the margin ; right valve flatter, the 

 posterior auricle well defined, small; both valves similarly sculptured 

 with nearly equidistant thin lamellae, which, when perfect, curve forward 

 and touch the rising curve of the next succeeding lamella ; an abso- 

 lutely perfect specimen would therefore present a series of equal, smooth, 

 concentric waves, falling almost vertically from the anterior hinge 

 margin and curving in a subcircular sweep around to the depression 

 which marks off the posterior auricle in either valve. Practically, 

 however, the fragile lainelke never retain more than traces of their per- 

 fect state and present a series of very sharp elevated concentric lam- 

 inae following the lines of growth and separated by narrow nearly 

 equal intervals, averaging on the whole four or five to the length of a 

 millimeter, radially measured; the umbones are small and prominent, 

 reaching slightly above the cardinal margin ; the interior is smooth 

 and polished; there is no radiating sculpture; the ligament is small 

 and subcentral ; there are no transverse rugae on the hinge margin, and 

 no internal liroe. Maximum altitude of the shell 9; maximum lati- 

 tude 8.5 ; diameter, 4.4 mm . 



Hab. — U. S. Fish Commission Station 2383, in 1,181 fathoms, mud, 

 between the delta of the Mississippi and Cedar Keys, Gulf of Mexico ; 

 bottom temperature 39°.8 F.; Station 2751, off St. Kitts, in 687 fathoms, 

 ooze; and 2760, 90 miles north of Ceara, Brazil, in 1,019 fathoms, tem- 

 peratures 39°.9 and 39°.4, respectively. 



This very simple and yet very characteristic little species seems to 

 stand in need of no comparisons, as it is not sufficiently similar to be 

 easily mistaken for any of the known species. 



Family LIMiD.F:. 



Genus LIMA Bruguiere. 



Subgenus LIMATULA S. Wood. 



Limatula setifera Dall. 



Plate xiv, Fig. 10. 



Limatula setifera Dall, Bull. Mus. Comp. Zool., xn, p. 224, 1886. 



Hab.— From North Carolina to Barbados in 50 to 450 fathoms, col- 

 lected by the Albatross at Stations 2612 and 2646. 



