BALL : MOLLUSCA AND BRACHIOPODA. 375 



lete toward the ends of the shell ; near the base are five close concentric striae 

 which extend the length of the margin, decidedly finer than the ripples ; interior 

 polished, margins entire, pallial sinus distinct ; hinge with about fifteen anterior 

 and thirteen posterior teeth, separated by an inconspicuous chondrophore. 

 Length of shell, 6.2. ; of anterior end, 3.0; alt. 3.8; max. diam. 3.0 mm. 



U. S. S. " Albatross," station 2799, Panama Bay, in 29^ fathoms, mud. U. S. 

 N. Mus. 110,690. Also at stations 2794, in 62 fatlwms, sand, bottom temperature 

 59°.5 F. ; 2801, in 14, and 2803 in 26 fathoms, mud. 



The sculpture varies^in strength a good deal for so small a shell ; occasionally 

 the concentric sculpture covers the whole of the valve, and now and then one is 

 seen which seems almost wholly smooth. 



Leda ( Jupiteria) lobula Dall, n. sp. 



Shell small, olivaceous, slightly inequilateral, rounded at both ends, the anterior 

 a little shorter ; anterior dorsal slope slightly convexly arcuate, posterior straight ; 

 the beaks, capped with a distinct protoconch, low and nearly vertical ; both ends 

 rounded, the anterior broader; external scul})ture of regular rounded, elevated 

 concentric threads with wider intervals, evenly covering the whole disk but 

 stronger in the middle of the shell ; interior polished, hinge with nine teeth on the 

 posterior side of the beaks, and about thirteen on the anterior, the chondrophoric 

 pit confined to the hinge line and very inconspicuous. Length, 4.7 ; alt. 3.2 ; 

 diam. 1.5 mm. 



U. S. S. " Albatross " station, 3422, in 141 fathoms, mud, off Acapulco, Mexico, 

 bottom temperature 5 3°. 5. 



This shell may not be fully mature, but as far as now appears it is not the young 

 of any of the known species of this region. It is remarkable for its oval shape, 

 which if characteristic of the fully adult would hardly allow it to be regarded as 

 a member of this section of the genus. 



Leda (Leda) costellata Sowerbt. 



Nucida costellata Sowerby, P. Z. S. London, 1832, p. 108; Conch. 111.. Nucula. 

 fig. 8; Hanley, Tlies. Conch., 3, Mon. Nuculacea, p. Ill, pi. 228. fig. 59. 



Gulf of California to Panama. U. S. S. " Albatross," station 2823, in 26 fath- 

 oms, sand. U. S. N. Mus. 96,424. 



This species, with L- decora and concinna A. Adams, has a very different as- 

 pect from those of the L. pernula type with which they are associated. 



Leda (Leda) cordyla Dall. n. sp. 



Plate 6, ngures 6, 7. 



Shell very small, very inequilateral, rostrate, olive green, strongly concentri- 

 cally sculptured ; beaks high, pointed, slightly opist bogy rate, showing a small 



