DALL: MOLLUSCA AND BRACHIOPODA. 405 
lated, the posterior apparently nearly smooth ; hinge line short, straight; interior 
smooth, a pair of small auricular crura present; the hinge line with a minute cen- 
tral pit and two relatively large transversely sharply striated, elongate areas rep- 
resenting a permanent provinculum. Height and length, 3; hinge line, 2.5; 
diameter, 1.0mm. A single valve from near the Straits of Magellan, apparently 
the same species, measures 7 mm. in height. 
U.S. 8S. “Albatross,” station 2799, in Panama Bay, in 291 fathoms; also at 
station 2784, in 194 fathoms, mud, bottom temperature 51°.9 F. U.S. N. Mus. 
110,708. 
The hinge line of this species is very much like that of P. (Pseudamusium) 
thalassinus Dall, described in the “‘ Blake ” report, 
Pecten (Cyclopecten) cocosensis Datt, n. sp. 
Plate 6, figures 1, 3. 
Shell small, suborbicular, translucent whitish, irregularly painted with opaque 
white, red, and ferruginous brown, in lines, zigzags, or clouded patches; there are 
also visible on the right valve in some of the specimens whitish rays which would 
give the impression until the interior is examined that the shell belongs to the 
Propeamusium group; ears subequal, small, the anterior larger, in the left valve 
elegantly minutely reticulated and at the hinge line adorned by a series of small, 
close-set, short, sharp spines; in the right valve the sculpture of the ears is very 
similar, but the lines are less close and sharp and the anterior auricle has a deep 
triangular byssal sulcus, without a noticeable fasciole or a ctenolium; left valve 
with the umbo sharp, small, and prominent, the disk nearly smooth, with faint 
radial striae which near the submargins become more regular and sharp, especially 
behind; right valve with a less prominent umbo, the surface polished, the ventral 
margin flexible, and reflexed when closed ; sculpture of fine, close, regular concen- 
tric lines with wider flat interspaces ; interior smooth, polished, without radial 
lirae; the hinge line with two well-marked transversely striated provincular areas. 
Height of shell, 8.7; breadth, 9.0; hinge line, 5.0; diam. 2.0 mm. 
U.S. 8. “ Albatross,” station 3369, near Cocos Island, Gulf of Panama, in 52 
fathoms, rocky bottom, temperature 62°.2 F. U.S. N. Mus. 122,870. 
The faint white rays on the right valve of this shell look so much like Propea- 
musium that until I separated the valves of one of the specimens I had no doubt 
it belonged to that group. 
AMUSHUM Bouten. 
PROPEAMUSIUM De Grecortio. 
Amusium (Propeamusium) malpelonium Da tt, n. sp. 
Piate 6, figure 9. 
Shell suborbicular, of a dirty white color, very thin and fragile, with small sub- 
equal ears, moderately convex; beaks low, prodissoconch small, swollen, slightly 
