DALL: MOLLUSCA AND BRACHIOPODA. 385 



of a minute, subinternal resilium; beaks small, low, adjacent, nearer the anterior 

 end ; lunule and escutcheon present but practically linear ; anterior slope slightly 

 couvexly arcuate, anterior end evenly rounded; posterior dorsal slope slightly 

 concavely arcuate to an angle near the end of the hinge plate ; posterior end 

 almost truncate, very bluntly rounded, compressed, wider than the anterior end ; 

 basal margin subparallel with the posterior dorsal, couvexly gently arcuate ; inte- 

 rior porcellanous wliite ; scars moderately distinct, pallial sinus deep, wide, 

 rounded in front ; hinge with twenty anterior and about twenty-seven posterior, 

 short, folded, delicate teeth ; a smooth gap between the two series, in the upper 

 edge of which can be detected traces of the obsolete resilium ; valve margins 

 entire. Lon. of shell, 22.5 ; of beaks behind anterior end, 8.5 ; alt. 12.5 ; diam. 

 8.0 mm. 



U. S. S. "Albatross," station 3374, southwest of Malpelo Island, Gulf of 

 Panama, in 1823 fathoms, ooze, bottom temperature 36°. 4 F. U. S. N. Mus. 

 122,906. Also at station 3361, in 1471 fathoms, ooze, temperature 36°. 6 F., and 

 3381, in 1772 fathoms, green mud, temperature 35°. 8 F. 



Remarkable for its light yellow color, its surface devoid of radial sculpture or 

 indented margin, and its bluntly truncate posterior end. In the latter character 

 and its subequal division of the hinge teeth it recalls Neilo, but is without the 

 rostration of that form. 



MINORMALLETIA Dall, sect. nov. 



Shell small, blunt, plump, with amphidetic ligament, no resilium, the pallial 

 sinus large, no radial depressions or sculpture. 



Malletia (Minormalletia) arciformis Dall, n. sp. 



Plate 15, flgurea S, 6. 



Shell very thin, inflated, rounded-quadrate, inequilateral, finely concentrically 

 striated, of a dull olivaceous color ; hinge line nearly straight, subaugulate where 

 it joins the semicircular arc of the posterior end ; anterior end shorter, narrower, 

 rounded ; base rather straight ; beaks low, very anterior, prosocoelous over a 

 narrow amphidetic ligameut; hinge line interrupted with ten anterior and about 

 thirteen posterior teeth ; muscular impressions deep, a large pallial sinus below 

 the posterior scar, confluent with the pallial line below; interior of the valves 

 whitish, earthy. Lon. 10.6 ; alt. 7.0 ; diam. 6.0 ; beak behind anterior end, 

 3.3 mm. 



U. S. S. "Albatross," station 3417, off Acapulco, Mexico, in 493 fathoms, 

 mud, bottom temperature iO°S F. U. S. N. Mus. 122,926. 



Though more rounded below and behind, this has a profile not dissimilar *» 

 that of Area (Fossu/arra) adamsi E. A. Smith. 

 VOL. XLin. — NO. 6 26 



