10 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 54. 



but 4 ribs (separated by rather acute interstices, as in interfossa) 

 on the lateral areas, 13 on the anterior valve, and but 16 narrow rib- 

 lets on the central areas, the latter connected by irregular wrinkles 

 rather than transverse bars. The anterior valve has only 8 sHts, and 

 the convex, nondentate sinus of the remaining valves is also distinctive 

 if correctly observed. The dorsal girdle scales are said to be weakly 

 striate. 



7. craticulatus (Gould) differs from both the Albatross species in 

 the far more numerous riblets of the lateral areas ("8-10"); a-nd of 

 the anterior valve ("about 50"), the minute latticing of the central 

 areas, and the fact that the teeth of the head valve are said to be 

 "distinctly notched or nicked at the edges and deeply, coarsely 

 grooved outside." The girdle scales are described as striate. 



7. coreanicus (Adams and Reeve) is insufficiently known and hence 

 not liable to comparison with the above species in any certain fashion 

 at the present time, though Pilsbry * has suggested a possible identity 

 with 7. craticulatus. 



The only other Lepidozona which I can find to have been recorded 

 from this region is 7, mertensii (Middendorff), a much more coarsely 

 sculptured species, with which none of the Albatross forms are likely 

 to be confounded. 



ISCHNOCHITON (LEPIDOZONA) PILSBRYANUS, new species. 



Plate 6, figs. 5-9; plate 7. 



Description. — Animal small, elevated, the sides only slightly con- 

 vex; maximum transverse diameter a little less than half the length, 

 or of shell alone about three-sevenths the length. 



Anterior valve rounded, conical, its slope straight in front, becom- 

 ing slightly convex on the sides (pi. 7, fig. 1). Interior smooth, 

 marked with a series of about 13 delicate radiating lines correspond- 

 ing to the marginal slits; teeth beveled, slightly rugose at the edges 

 and obscurely and irregularly striate outside (pi. 7, fig. 2). 



Median valves elevated, not beaked, high arched, sharply angled at 

 the jugum, the side slopes nearly straight or very shghtly convex. 

 Sutural laminae short and broad; connected across the sinus by a 

 delicate, scarcely projecting, very weakly dentate plate, the outhne of 

 the latter varying from strongly convex in the second valve to shghtly 

 concave in the more central valves, and showing apparently but about 

 8 slits, though there are some 10-12 of the incised lines wliich ordi- 

 narily correspond. Eaves short, relatively sohd (pi. 7, figs. 1-4). 



Posterior valve with mucro nearly median ; posterior slope strongly 

 concave; sutural laminae as described above, the minute shts and 

 lines each about 8 in number; similar lines radiate from the mucro 



J Man. Conch., vol. 15, p. 85. 



