i.i ri ix >ri i i i 



, and without the dinu'V hlaekish pai nt in- of either. / 

 crl/ntu.< is narrower, higher, and \\itli a -harper medi:m aiiL'Ir. | M 

 L. fnli t/iiiiifn.* the middle valve- are ihortei from front t<. liaek, tli.' 

 sutural lamina- .-mailer and much more tri;iii'_:ular. Th- 

 siirii of a niucro on these valves, hut in /,. y,/-/-///-//,,,////.* t in TO \ a 

 beginning of one, <|iiitc perceptible. The latter i.- a pn.pi.rt ionallv 

 wider and. Hatter species, with a stronger and more prominent girdle 

 densely set with elongated silvery scales like short <titf'_ r r;i\ 1 

 these form a pretty fringe at the periphery. The sculpture foil 

 tlu i pattern of I,, canc.dltitn*, hut, the lateral areas are less r|<arl \ 

 defined, the granules are more clearly cut, more regularly arranged 

 and larger than in any of the species hitherto known. There are 

 twelve gills on each side, reaching forward to about the middle of 

 the sixth valve. (Dall.} 



L. BELKNAPI Dall. PL 1, figs. 18-22. 



Shell elongated, much elevated, dorsally angled; whitish, more 

 or less tinged with ashen or black. Valves elevated, with distinct 

 apices ; mucro central, conspicuous. Sculpture as in L. alveolus, 

 but the granules of the dorsal areas sparse, and disposed in quin- 

 cunx. Posterior valve concave below the apex, sinuated behind. 

 Girdle narrow, having delicate spicules toward the margin. {Dall.) 



Length 10, breadth 3 mill.; divergence 90. 



North Pacific Ocean in lat. 53 08' N. t Ion. 17 19' IF., at a depth 

 of 1006 fms. ; off Cape Bolinas, Luzon, Philippines, 1050 fins. 



LeptochitonbelknapiDAL^PTOc. U. S. Nat. Mus. 1878, p. 1, 

 Jan., 1878 ; I. e. p. 317. HADDON, Challenger Kep. xv, p. ID, t. 1, 

 f. 2 ; t. 2, f. 2. 



This specimen much resembles L. alveolus, to which I at first 

 referred it. A careful microscopical examination, however, shows 

 differences which I am disposed to consider specific; but I have 

 but one specimen, and others might show modifications in the^e 

 particulars. The differential characters are as follows: In afr- 

 the pustules are distributed evenly, closely and in no pattern what- 

 ever, all over the surface. In belknapi, they are more widely 

 separated and arranged in quincunx on the dorsuin, the s\ 

 >eeming to radiate from the median dorsal line. In a/tW//.< the lat- 

 eral areas are barely perceptible. In belknapi they are raised, con- 

 centrically rugose, and the pattern of the pustular arraiiL. r cm! 

 different and more irregular than that on the dorsum. In belktiapi 



