428 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Verticordiudae. 
LYONSIELLA Sars. 
Lyonsiella pacifica Datt, n. sp. 
Shell small, plump, white, subquadrate, microscopically radiately closely granu- 
lately striate, covered more or less densely with adherent sand grains and foram- 
inifera; beaks large for the size of the shell, high, prosogyrate with a small 
cordate impressed area in front of them; anterior end very short, small, posterior 
longer, wider, rounded; base arcuate, prominent in the middle ; no external liga- 
ment; surface closely covered with radial rows of extremely minute granules. 
Lon. 8; alt. 2.7; diam. 1.8 mm. 
U.S. S. “ Albatross,” station 4693, Mid Pacific, northwest point Sala y Gomez 
Island, bearing N. 82° E., fifteen miles, in 1142 fathoms, gravel, bottom tempera- 
ture 35°.4 F. U.S. N. Mus. 110,583. 
Only a single specimen of this finely granulose species was obtained. In form 
it is not unlike the much larger L. papyracea Smith, figured in the ‘ Challenger ” 
Report, but the sculpture is quite different and the shell is proportionately more 
compressed. It is impossible to determine whether the specimen is adult or not, 
but it has a mature aspect. 
Poromyacidae. 
POROMYA Forzes. 
Poromya Forbes, Aegean Rep. Brit. Assoc., 1844, p. 103; type, P. anatinoides 
Forbes, /. c., = P. granulata Nyst (as Corbula). 
Embla Lovén, Ind. Moll. Scand. Occ., 1846, p. 46; type, E. korenii Lovén (= granu- 
lata Nyst). 
Ectorisma Tate, Trans. Roy. Soc. Austr., 1902, 15, p. 127, pl. 1, fig. 3; Hedley, 
Proc. Lin. Soc. N. S. Wales, 1906, p. 539; type, LE. granulata Tate (not of 
Nyst). Hedley, Rec. Austr. Mus., 1907, 6, p. 302, makes Tate’s species prob- 
ably identical with Poromya laevis Smith, of the ‘‘ Challenger ”’ Report. 
Poromya perla Da tt, n. sp. 
Plate 18, figures 2, 5. 
Shell small, globose, exceedingly thin, whitish, subequivalve, subequilateral, 
with very high swollen, strongly prosocoelous beaks; no lunule or escutcheon, 
but the posterior hinge margin of the right valve overlaps that of the left, with a 
single, strong, radial rib near the edge, which does not appear in the opposite 
valve; anterior margin of the valves evenly rounded into the nearly semicircular 
base; posterior slope straight; posterior end short, somewhat compressed and 
