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 
convexly 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, convexly gently arcuate; inte- 
rior porcellanous white; 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. i 
U. 8. 8. “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 Datzt, sect. nov. 
Shell small, blunt, plump, with amphidetic ligament, no resilium, the pallial 
sinus large, no radial depressions or sculpture. 
Malletia (Minormalletia) arciformis Datt, n. sp. 
Plate 15, figures 5, 6. 
Shell very thin, inflated, rounded-quadrate, inequilateral, finely concentrically 
striated, of a dull olivaceous color; hinge line nearly straight, subangulate 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 ligament; 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 40°.6 F. U.S. N. Mus. 122,926. 
Though more rounded below and behind, this has a profile not dissimilar to 
that of Arca (Fossularca) adams E. A. Smith. 
VOL. XLIII. — NO. 6 25 
