402 BULLETIN ; MUSEUM OF COMPARATIVE ZOOLOGY. 
threads on a light pink background covered with the superficial reticulum; poste- 
rior ear smaller, with two or three radial obscure threads; disk with about fourteen 
radial ribs (none intercalary) subequal and equally spaced; the whole surface 
covered with a fine, closely woven reticulum of minute rectangular scales, when 
perfect coalescent at the surface, when the surface is eroded presenting a minute 
cellular reticulum, when this is eroded the surface still shows fine regular reticular 
markings. When the crust is perfect over a rib it appears keeled, when the crust 
is removed the rib itself is seen to be rounded, the interspaces also are not chan- 
nelled but roundly excavated ; interior polished, the coloration shining through ; 
hinge margin straight, with a small medial pit, the margin showing conspicuous 
traces of the provincular striation; there are no crura, the peripheral margin of 
the disk is irregular. Alt. of valve, 16; lat. of valve, 13; of hinge line, 8 mm. 
Collected on the beach at Easter Island, by the “‘ Albatross” party. U.S. N. 
Mus. 110,765. 
This single valve would perhaps not have been worthy of description were it 
not that it seems to belong to the group of specjes called Hinnites, and possesses 
such a remarkable surface. I have elsewhere expressed the opinion that the dif- 
ferent species of Hinnites are more intimately related to various groups of Pecten 
than they are to each other, and that probably there is no direct genetic relation 
between the fossil species. The “genus”? Hinnites may be regarded as composed 
of “sports” from the Chlamys group of Pecten. 
Pseudamusium HH. anp A. Apams. 
Pecten (Pseudamusium) liriope Da tt, n. sp. 
Shell small, fragile, whitish, subcircular; convex (left) valve with small sub- 
equal ears finely concentrically lamellose; disk with extremely fine, close, radial 
threads with nearly equal interspaces; crossed by fine, concentric lamellae, with 
wider interspaces, more distant on the beaks, closer toward the margin; interior 
glassy, the sculpture shining through ; right valve similarly sculptured, except 
that the radial threads are obsolescent and the concentric lamellae more obvious; 
anterior ear longer with a wide byssal sulcus and fasciole, a single radial thread 
bordering the fasciole; margin of the disk flexible. Alt. 7.5; lat. 8.0; hinge 
line, 4.5; diam. 2.5 mm. 
U. 8. S. “ Albatross,” station 3392, Gulf of Panama, in 1270 fathoms, hard 
bottom, temperature, 36°.4 F. U.S. N. Mus. 122,869. 
A peculiar thing about the sculpture of this little shell is that, looked at in one 
light, only the radial, in another only the concentric sculpture is visible, and thus 
there is no effect of reticulation to speak of, yet there is little difference in the 
strength of the two kinds of sculpture. 
Pecten (Pseudamusium) neoceanicus Datt, n. sp. 
Pilate 9, figure 4. 
Shell small, thin, brownish white, concentrically undulate and with both valves 
similarly reticulately sculptured, equivalve, somewhat equilateral ; beaks (showing 
