420 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



rounded, base gently and evenly arcuate ; in the left valve a long, narrow, and 

 deeply impressed luuule ; 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 sliell ; 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 luuule with a 

 projecting angle distally ; pallia! sinus obliquely ascending, large, subaugular, 

 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. S. " Albatross," station 3355, in the Gulf of Panama, in 182 fathoms, 

 mud, bottom temperature 54°. 1 F. U. S. N. iJus. 122,935. 



The only other species of this group known from tlie region is T. (P-) pristi- 

 pkora Dall, which cannot be confounded with the present shell, of which, unfortu- 

 nately, only one left valve was obtained. 



Moerella Fischer. 



{Moera Adams, not of Leach ; Maera Adams, not of Leach ; Donacilla Gray, 

 not of Lamarck.) 



Tellina (Moerella) chrysogona Dall, n. sp. 



Plate 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 

 arc close-scf, 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, 13 ; of beaks behind the anterior end, 5 ; alt. 10 ; diam. 5 mm. 



