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) subcqual 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 erod(;d 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 species 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. 



Pseudamusitim II. a>d A. Adams. 

 Pecten (Pseudamusium) liriope Dall, 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. S. 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 radi.il, 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 Dall, n. sp. 



Plate 0, flKiire 4. 

 Shell small, thin, brownish white, concentrically undulate and with both valves 

 similarly reticulately sculptured, equivalve, somewhat equilateral ; beaks (showing 



