so. 2223. CHITONS FROM THE NORTHWEST PACIFIC— BERRY. 13 



addition to a number of smaller and less definitely arranged bristles 

 and tufts of spines. The figure of one of the large bristles by Car- 

 penter, which appears in the Manual (vol. 14, pi. 62, fig. 86) is very 

 misleading, and I can only surmise that he must have mistaken the 

 white or light-colored bands of spines, revealed by these specimens 

 under a sufficiently high magnification, for spineless areas. When 

 perfect the light and dark brown bands in alternation are a conspicu- 

 ous feature of the bristles. An attempt is made to convey some 

 idea of this in the accompanying drawing (pi. 9, fig. 4). Here 

 it also appears that the spinose armature of all the larger bristles 

 is exceedingly heavy, the spines being crowded upon one another 

 in a fashion not conspicuously different from that observable in 

 P. velata Carpenter. These two species are indeed exceedingly 

 close and resemble one another much more nearly than either pat- 

 terns the various Alaska-Bering Sea forms, with which they have 

 at times been confounded. 



In addition to those mentioned by Pilsbry, the following differences 

 from California specimens of P. velata may be noted: 



1, the shorter, wider valves. 



2, the flatter outline. 



3, the conspicuously marbled slate and buff coloration. 



Outline drawings of the valves (pi. 9, figs. 1-3) and the typically 

 Mopalioid radula (pi. 9, figs. 7-8) aie here given, the latter for the 

 first time. 



The ctenidia number about 26 on each side. 



PLACIPHORELLA BOREALIS Pilsbry, 1892. 



Plate 8, figs. 3-5; plate 10. 



1886. Placiphorella stimpsoni Dall (part), Proc. U. S. Nat. Mus., vol. 9, p. 210. 

 1892. Placiphorella borealis Pilsbry, Man. Conch. (1), vol. 14, p. 309, pi. 66, 

 figs. 14-17. 



Material. — Station 4803; 228 fathoms; bottom of black sand and 

 gravel; bottom temperature 35.4° F.; off Cape Rolhn, Simushir 

 Island, Kuril Group; June 24, 1906 (seven specimens) [S. S. B. 94]. 

 Four specimens are entered as Cat. No. 215633, U.S.N.M. 



Remarks. — The shell of this species is the subject of a careful and 

 detailed description by Pilsbry, but as the girdle characters have 

 hitherto remained unknown it seems worth while to describe them 

 in some detail. The dorsal surface of the entire girdle is covered 

 with very minute pointed spinelets, rather heavily distributed. 

 Among these one occasionally finds scattered spines or groups of 

 spines slightly larger in size, a condition more eVident near the 

 margin than elsewhere. In addition occur the usual armored 

 bristles characteristic of the genus, the most conspicuous being a 

 fairly regular series bordering the entire anterior lobe a short dis- 



