ball] new species of sheels 171 



number against about 18 in hericeus; tbe interior is less colored. 

 Alt., 69; Ion., 70; diameter, 24; Ion. of binge line, 32 mm. 



U. S. S. Albatross, station 5021, Okhotsk Sea, September 27, 

 1906, in 73 fathoms. U. S. Xat. Mus., 110,462. 



Tbe lower valve is white, but its sculpture similar to that of the 

 upper valve. The station is on the east coast of Sakhalin Island. 



Genus CREXELXA Brown 

 CRENELLA GRISEA Dall, n. sp. 



Shell thin, oblique, elongate, rounded-quadrate when adult, the 

 young specimens relatively shorter ; surface of a grayish olivaceous 

 color, with lighter and darker zones, brilliantly polished, with faint, 

 irregular traces of fine obsolete radial striation ; beaks inconspicuous, 

 hinge line gently arcuate, with a minutely denticulate small lamella 

 directly under the beaks ; the margin behind the beaks with narrow 

 internal elongate ligament, behind which are sharp minute inter- 

 locking denticulations of the margin, beyond which the margin is 

 minutely crenulate ; interior bluish perlaceous ; hinge line behind the 

 beaks slightly rounded and produced, but not quite angulate. Long- 

 est extension of shell, 12; dimension at right angles to this, 8.5; 

 diameter, 7 mm. 



U. S. S. Albatross, stations 4782, off east end of Attu Island, 

 June 9, and 4784, June 11, 1906, in 57 and 135 fathoms respectively. 

 U. S. Xat. Mus., 110,464 and 110,465. 



Peculiarly shaped and colored, but not identical, as far as can 

 be told, with any of A. Adams' imperfectly described nominal species. 



CRENELLA DIAPHANA Dall, n. sp. 



Shell large for the genus, tumid, extremely thin, elongate-ovate, 

 pale horn-color, finely minutely radially sculptured, the interspaces 

 channeled distally, biit narrower than the radii ; beaks prosocoelous, 

 prominent : hinge line very short, the valves nearly equilateral, the 

 sides similar, the base medially produced ; internal ligament strong, 

 anteriorly divided, the margins minutely crenulate, but not inter- 

 locking, except immediately under the beaks; alt., 18; Ion., 14; 

 diameter, 13 mm. 



U. S. S. Albatross, station 5092, October 26, 1906, in 70 fathoms. 

 Gulf of Tokio. U. S. Nat. Mus., 110,466. 



The shell is so equilateral that it looks like the dorsal valve of a 

 delicately sculptured Tercbratulina. 



