DALL: MOLLUSCA AND BRACHIOPODA. 413 



Aligena borniana Dall, n. sp. 



Plate 10, flgure 2. 



Shell small, thin, white, subquadrate witli a slight mesial contraction, the 

 periostracum pale straw color, silky, microscopically concentrically closely striate ; 

 beaks low, posterior, prodissocouch 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 Dall, 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. 

 ROCHEFOKTIA Velain. 



(Tellimya H. and A. Adams and Carpenter, Mysella Angas, not Tellimya Brown. 

 1827.) 



Rochefortia mabillei Dall, n. sp. 



Shell small, smooth, inequilateral, oblique, ratlior inflated ; surface with faint 

 lines of growth and obscure indications of one or two resting stages; the 



