MUSEUM OF COMPARATIVE ZOOLOGY. 255 
The shell when living is of a brilliant white, covered with a fine smooth but 
not polished straw-colored epidermis. The ligament is wholly external, deli- 
cate, and nearly hidden in a groove just behind the beaks. There are twelve 
anterior and twenty-eight posterior teeth, which dwindle to a spot just under 
the beaks, below which is a little flat or subconcave space very like a shelf for 
a cartilage, which, however, does not exist. The measurements of the fully 
adult form are, max. lon. 15.0 ; max. alt. 11.2 ; max. diam. 9.0mm. There 
is a polished space in front of the beaks where the concentric waves fade out, 
faintly margined by an obsolete radius or two, but not otherwise differentiated ; 
and immediately in front of and close to the beaks is a very small rounded area, 
over which the epidermis is of a darker color than elsewhere, but apparently 
not marked by sculpture. The pallial line is entirely simple, and the interior 
of the shell brilliantly polished, with a tendency to iridescence, though not 
pearly. 
Malletia (Tindaria) Smithii Dat. 
Malletia cuneata E. A. Smith, Chall. Rep. Lam., p. 247, pl. xx. figs. 10, 10a, 1885. 
Not M. cuneata Jeffreys (1876), P. Z. S., 1879, p. 586, pl. xlvi. fig. 10. 
A dead valve of this species was dredged by Sigsbee in 450 fms., off Havana. 
The Challenger specimens were taken in 390 fms., off Culebra Island. A 
specimen was dredged by the U.S. Fish Commission at Station 2119, near 
Grenada, in 1140 fms., bottom temperature 39°.5 F. This measured 7.75 mm. 
in length, and had nine anterior and twenty-two posterior teeth, counting all 
the small ones. 
As my friend, Mr. E. A. Smith, in his valuable report on the Challenger 
Lamellibranchs, has overlooked the prior use of his specific name by Jeffreys, it 
gives me much pleasure to propose the name of Smithii for this very elegant 
little shell. 
Section NEILO Apams. 
Malletia (Neilo?) dilatata Partrprr. 
Leda dilatata Philippi, Dall, Bull. M. C. Z., IX. p. 125, 1881. 
Neilo dilatata Seguenza, Nucul. Terz., 1877, p. 1184. 
Habitat. Off Morro Light in 292 fms., two right valves. 
This agrees exactly with the Italian fossils. There is no cartilage pit, but a 
wide subtriangular gap in the line of teeth, and a groove for an external liga- 
ment. I cannot see that the hinge without the soft parts offers decisive evi- 
dence of the place to which this species should be referred. It is probably a 
Malletia, and belongs in the vicinity of M. arrouana Smith, in which the gap 
in the line of teeth would seem to have become closed. 
