378 bulletin: museum of compakative zoology. 



The Nacula excisa of Philippi, called Malletia excisa by Jeffreys, is a species 

 of this group ; the chondrophore is between the two series of teeth and well- 

 marked. 



Leda (Spiniila) calcar Dall, n. sp. 



Plate 10, figures 1, 10. 



Shell compressed, tiglitly closed, acutely rostrate, brilliautly polished, smooth, 

 covered with au olivaceous periostracum, inequilateral ; beaks small, sUghtly ele- 

 vated, adjacent, vertically overhanging a delicate, rather long, amphidetic liga- 

 ment, which extends about equally in front of and behind the beaks ; lunula 

 lanceolate, long, narrow, compressed, the valve margins most prominent, delimited 

 by faintly impressed lines ; anterior dorsal margin gently arcuate ; escutcheon 

 similar to the lunule but smaller and limited by elevated lines, outside of which is 

 a depressed space bordered externally by a strong radial keel extending from the 

 beaks to the extremity of the rostrum ; posterior dorsal margin nearly straight, 

 posterior end acutely angular, with a wide shallow sulcus below, setting off the 

 rostrum ; anterior end rounded, slightly attenuated, basal margin exclusive of the 

 rostrum, evenly arcuate ; surface of the disk smooth or with faiut concentric 

 irregularities due to growth, and occasional faint microscopic radial striae which 

 seem to be confined to the periostracum ; interior porcellanous, polished ; hinge 

 with 16-17 anterior and about the same number of posterior teeth, the two series 

 separated by a small triangular pit containing a well-developed though small 

 black resilium, plainly visible from below in the closed valves ; according to the 

 lines of growth the young shells will be even more acutely rostrate than the 

 adults. Lon. of shell, 15.2 ; of rostrum, 2.5 ; of posterior dorsal slope, 9.5 ; alt. 

 8.2; diam. 4.0 mm. 



U. S. S. "Albatross," station 4658, off the Peruvian coast, in S. Lat. 8° 30', 

 W. Lon. 85° 3G', in 2370 fathoms, green mud, bottom temperature 35°. 3 F. 

 U. S. N. Mus. 110,573. 



This is a remarkable form which I have found it difficult to place. 



Leda (Spinula) calcarella Dall, n. sp. 



Shell resembling L. calcar, but smaller, more compressed proportionately, with 

 a shorter rostrum and blunter posterior end, feebler dorsal keels, and with, on 

 the disk near the base, six or eight impressed lines not coincident with the lines 

 of growth, and more or less resembling the lines on Yoldia lanreolata of authors. 

 Lon. of shell, 9.0; of rostrum, 0.7; of dorsal slope, 5.0 ; alt. 5.7 ; diam. 2.0 mm. 



U. S. S. " Albatross," station 4656, off the coast of Peru, iu S. Lat. 6° 55' 

 and W. Lou. 83° 34', in 2222 fathoms, green mud, bottom temperature 35°. 2 F. 

 U. S. N. Mus. 110,575. 



This form is not fully adult and might be regarded as the young of Leda calcar 

 were it not that the profile of the latter, as indicated by lines of growth, is quite 



