dall: mollusca and bkachiopoda. 355 



even more angular dorsally, lias the posterior mucro nearer to the posterior mar- 

 giu, aud has the lateral areas of the intermediate valves prominently concentrically 

 rippled. 



Lepidopleurus incongruus Dall, n. ep. 



Animal with the gills forming a very short posterior row; girdle narrow with 

 extremely minute, close-set spines, giving the effect of a naked, velvety surface. 

 Intermediate valves pale brown, the median line slightly obtusely angular; 

 jugum slightly mucronate behind, the jugal area sculptured with very fine, close- 

 set, rounded, longitudinal threads; pleural tracts with ten or twelve larger threads 

 with wider, flat interspaces, the threads sometimes breaking off abruptly, leaving 

 a double-width interval the rest of the way; lateral areas prominent, very finely 

 granulose, conspicuously concentrically rippled; anterior plate with feeble con- 

 centric ripples and similar granulation; posterior valve with prominent subcentral 

 mucro, the central area sculptured like the pleural tracts of the preceding valves, 

 the posterior area like the anterior valve; penultimate valve with a length of 2.3, a 

 width of G.O, aud an altitude of 2.5 mm. Articulations as usual in the genus. 



U. S. S. "Albatross," station 335 Jt, Gulf of Panama, in 322 fathoms, mud, 

 bottom temperature 4G° F. U. S. N. Mus. 122,969. 



This species appears to have a unique sculpture- An examination of the valves 

 figured in I'ilsbry's monograph for tlie whole family reveals none like it. 



Lepidopleurus luridus Dall. 



Lepidopleurus luridus Dall, I'roc. U. S. Xat. Mus., 1902, 24, p. 556. 



U. S. S. "Albatross," station 3392, in Panama Bay, in 1270 fathoms, hard 

 bottom, temperature 3G°.4 F. ; and station 3393, in 1020 fathoms, mud, temper- 

 ature 36°.8. U. S. N. Mus. 109,027. 



Lepidopleurus farallonis Dall. 

 Lepidopleurus farallouis Dall, I'roc. U. S. Nat. Mus., 1902, 24, p. 557. 



U. S. S. " Albatross," station 3104, near the Farallones Islands, oflf Sau 

 Francisco, California, in 391 fathoms, coral, bottom temperature 41° F. ; U. S. 

 N. Mus. 109,025 ; and at station 3393, Panama Bay, in 1020 fathoms, mud, 

 temperature 36°. 8 F. 



Mesochitonia. 

 Cliitonidac. 

 rAI.I.ISTOriIITON Carpenter. 

 Callistochiton periconis Dall, n. sp. 



Animal small, of a jialc brownish color with a narrow dark girdle covered with 

 small, closely packed setose scales; middle valves with the sculpture oiC pklchfllus 



