16 MOLLUSES FBOM WEST COAST OF AMERICA— BALL. vol. xvm. 



sculpture of feeble, narrow, irregular concentric wrinkles, crossed by 

 fine, sbarp, ratlier distant incised lines; lunule narrow, elongate, bor- 

 dered by a faint ridge; escutclieon small, broader tlian long, set off by 

 an impressed line from the large j)osterior area, which is flattened but 

 not definitely limited, the margin of the valve projecting somewhat in 

 the middle line; base rounded in front, somewhat imi)ressed posteri- 

 orly; interior brilliantly nacreous, with a strong ijallial line and sub- 

 equal adductor scars; the pallial area more or less punctate; basal 

 margin denticulate; hinge with about 30 anterior and 15 posterior 

 teeth, strong, projecting, and somewhat angular; chondrophore nar- 

 row, pear-shaped, projecting forward from the hinge line. Height of 

 shell, 22.5; length, 35; diameter, 16 mm. 



U. S. Fish Commission station 339G, in 259 fathoms. Gulf of Panama; 

 temperature, 47.1° F. 



Tijpe.—lSo. 122896, U. S. X. M. 



This fine shell is one of the largest known, and peculiar from its elon- 

 gated shape and posterior attenuation. The periostracum seems to 

 have been thin, dull, and yellowish. 



LIMOPSIS COMPRESSUS, new species. 



Shell large, thin, compressed, with a yellowish-brown, pale, pilose epi- 

 dermis; surface reticulated with fine radiating striie and rather irreg- 

 ular elevated lines of growth; beaks low, but conspicuous, small, and 

 swollen; area narrow, long, about equal on each side of the beaks; 

 dorsal line straight, anterior end rounded, posterior produced, rounded; 

 interior white, smooth, with plain margins; posterior adductor scar 

 larger and lower than the anterior; ligament central, lozenge-shaped, 

 thin; hinge with about six i^osterior and eight anterior teeth, small, 

 obscure, separated by a wide edentulous space, and obsolete in senile 

 specimens. Length of shell, 15; height, 37; diameter, 17.5 mm., exclu- 

 sive of the hair-like processes of the periostracum. 



U. S. Fish Commission station 3382, in 1,793 fathoms,Gnlf of Panama; 

 temperature, 36° F. 



Tijpe.—^o. 122889, U. S. N. M. 



PHILOBRYA ATLANTICA, new species. 



Shell small, thin, short-mytiliform, covered with a conspicuous, thin, 

 greenish epidermis, prominent on the ribs and at the margin; valves 

 rather inflated, the beaks crowned with the subovate glochidial valves 

 of the nepiouic young, bordered by a narrow elevated margin, then 

 smooth and inflated for a short distance, then radiately ribbed, with 

 about 11 squarish elevated ribs, marked with projecting epidermis, 

 between which the margin is slightly' excavated; anterior end short, 

 projecting a little beyond the beaks; area linear, auiphidetic; ligament 

 internal, short, almost terminal; interior of valves smooth, the hinge line 

 rather broad, edentulous; the scars as in MytUus; the byssal gape very 

 narrow. Length of shell, 4; breadth, 3; diameter, 2 mm. 



