DALL: MOLLUSCA AND BRACHIOPODA. 413 
Aligena borniana Datt, n. sp. 
Plate 10, figure 2. 
Shell small, thin, white, subquadrate with a slight mesial contraction, the 
periostracum pale straw color, silky, microscopically concentrically closely striate ; 
beaks low, posterior, prodissoconch distinct, minute, rounded; subsequent sur- 
face minutely concentrically sculptured; anterior end longer, wider, evenly 
rounded ; posterior shorter, more rapidly descending and blunter; base nearly 
straight with a slight mesial inward curve; surface of the disk marked with 
minute, hardly visible, vermiculate, radial markings; interior, milk-white por- 
cellanous, scars hardly visible ; hinge edentulous, hinge line discontinuous below 
the beak, with a short, delicate, yellow-brown, narrow resilium, wholly internal. 
Lon. 14.2; of beak behind anterior end, 8.5; alt. 10.5; diam. 7.0 mm. 
U.S. S. “Albatross,” station 4732, Pacific Ocean, in South lat. 16° 32’, and 
West long. 119° 59’ in 2012 fathoms, globigerina ooze, bottom temperature 
34°.8 F. U.S. N. Mus. 110,585. 
This shell has very much the form of Bornia, but the hinge of Aligena. It is 
clearly distinct from any species of the group yet described. 
Aligena pisum Da tt, n. sp. 
Shell very small, smooth, with a prominent, narrow, slightly prosogyrate umbo ; 
valves suborbicular, feebly incrementally striated, covered with a pale periostra- 
cum which has a certain pearly lustre; there is no escutcheon or lunule, the 
margin is smooth and entire; ligament internal, opisthodetic, rather long ; hinge 
line infolded under the beak with, in the left valve, a single obscure tooth or 
nodular prominence; pallial line entire. Length of shell, 2.5; alt. 2.7; diam. 
about 1.5 mm. 
U.S. S. “Albatross,” station 2778, Magellan Strait, in 61 fathoms, mud, 
bottom temperature 48° F. U.S. N. Mus. 110,715. 
A single left valve of this minute species was obtained. 
Leptonidae. 
ROCHEFORTIA Veta. 
(Tellimya H. and A. Adams and Carpenter, J/ysella Angas, not Tellimya Brown. 
1827.) 
Rochefortia mabillei Datt, n. sp. 
Shell small, smooth, inequilateral, oblique, rather inflated ; surface with faint 
lines of growth and obscure indications of one or two resting stages; the 
