420 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
rounded, base gently and evenly arcuate; in the left valve a long, narrow, and 
deeply impressed lunule ; posterior dorsal slope convexly arcuate, near the pos- 
terior end obliquely truncate, bluntly pointed below ; a long, narrow ligament on 
a well-developed nymph lies in the furrow of a narrow, excavated escutcheon, 
twice as long as the ligament; disk polished, sculptured with numerous (about 
two to a millimeter), elevated, regularly spaced concentric lamellae, which are 
flattened down near the middle of the disk but more erect and crowded toward the 
ends of the shell; in the left valve a shallow channel extends from the umbo to the 
posterior basal angle of the shell; above the channel is a faint ridge, beyond 
which the concentric lamellae, near the dorsal margin, break up into short 
waves or segments which become more distant and elevated at the verge of the 
escutcheon ; interior polished, hinge line narrow, with three small cardinals, of 
which the anterior pair are closely adjacent; the margin under the lunule with a 
projecting angle distally; pallial sinus obliquely ascending, large, subangular, 
extending in front of the beaks on a level with the anterior adductor scar, entirely 
free from the pallial line below. Lon. of shell, 32; of part behind the beaks, 19; 
alt. 20; diam. of left valve, 4.5 mm. 
U.S. 8S. ‘ Albatross,” station 3355, in the Gulf of Panama, in 182 fathoms, 
mud, bottom temperature 54°.1 F. U.S. N. Mus. 122,935. 
The only other species of this group known from the region is 7. (P.) pris¢i- 
phora Dall, which cannot be confounded with the present shell, of which, unfortu- 
nately, only one left valve was obtained. 
Moerella Fiscuer. 
(Moera Adams, not of Leach; Maera Adams, not of Leach; Donacilla Gray, 
not of Lamarck.) 
Tellina (Moerella) chrysogona Da tt, n. sp. 
Piate 10, figures 4, 8. 
Shell small, solid, subtriangular, equivalve, inequilateral, polished, bright yellow 
fading into white about the margins; beaks smooth, pointed, rather small, with 
a strong opisthodetic external ligament; about a third of the disk near the beaks 
smooth, the remainder gradually developing regular, concentric, gradually more 
adjacent incised lines, and flattish interspaces, which on the posterior dorsal area 
are close-set, more elevated and conspicuous; anterior slope arcuate, longer, 
posterior shorter, more direct; anterior end broadly rounded, posterior bluntly 
pointed and bent to the right; base evenly arcuate; interior smooth, the centre 
of the disk an intense yellow; scars distinct, pallial line coincident with the lower 
half of the sinus, the bight of the sinus almost reaching the anterior adductor 
scar in both valves ; hinge normal, two strong laterals in the right valve. Lon. 
of shell, 18; of beaks behind the anterior end, 5; alt. 10; diam. 5 mm. 
