378 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
The Nucula 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 (Spinula) calcar Darı, n. sp. 
Plate 10, figures 1, 10. 
Shell compressed, tightly closed, acutely rostrate, brilliantly polished, smooth, 
covered with an olivaceous periostraeum, inequilateral; beaks small, slightly ele- 
vated, adjacent, vertically overhanging a delicate, rather long, amphidetic liga- 
ment, which extends about equally in front of and behind the beaks; lunule 
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 faint 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; accordiug 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. 
8.9; diam. 4.0 mm. 
U. S. S. “Albatross,” station 4658, off the Peruvian coast, in S. Lat. 8° 30’, 
W. Lon. 85° 36°, in 2370 fathoms, green mud, bottom temperature 359.3 F. 
U. S. N. Mus. 110,573. 
This is a remarkable form which I have found it difficult to place. 
Leda (Spinula) calcarella Datt, n. sp. 
Shell resembling Z. calcar, but smaller, more compressed proportionately, with 
a shorter rostrum and blunter posterior end, feebler dorsal keels, and with, o" 
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 lanceolata of authors. 
Lon. of shell, 9.0; of rostrum, 0.7; of dorsal slope, 5.0; alt. 5.7; diam. 9.0 mm. 
U. 8. S. “ Albatross,” station 4656, off the coast of Peru, in S. Lat. 6° 55’ 
and W. Lon. 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 
