282 REPORT ON ALBATROSS MOLLUSCA DALL. 



Subgenus LUZONIA Dall &, Smith. 



Both valves without lateral teeth, right valve with an anterior 

 cardinal tooth, left valve edentulous; exterior concentrically striate; 

 fossette narrow, parallel with the cardinal margin under the apex. 

 Type Ntcera philippinensis Hinds, from Luzon and Mindanao, Philippine 

 Islands. 



This is Section H of Smith's arrangement of 1885, in the Eeport on 

 the Challenger Lamellibrauchs, p. 37. 



Cuspidaria (Luzonia) chilensis sp. nov. 

 Plate xni, Fig. 13. 



Shell white, thin, polished, under a rusty brown, dull, caducous epi- 

 dermis; beaks not prominent, nearly central; anterior hinge-margin 

 thin, sloping evenly and then evenly rounded to the arcuate base; pos- 

 terior hinge-margin declining somewhat less, nearly straight, at the 

 end of the rostrum evenly rounded over, the end of the rostrum 

 being rounded, not truncate. On the rostrum is an obscure ridge 

 extending to the umbo; in front of this ridge is a wide shallow 

 sulcus by which the basal margin at the beginning of the rostrum is 

 rendered a little concave; there is a faint ridge or thread close to the 

 posterior hinge margin in the left valve, but none in the right; sculp- 

 ture of fine silky concentric lines, but no radii; interior polished, with a 

 few fine radiating stria? ; pallial line simple, not siuuated, vertically 

 truncate at the beginning of the rostrum ; hinge margin thin, edentu- 

 lous except for a small triangular lamina in the right valve in front of 

 the fossette; fossette narrow, directed backward, parallel with the 

 hinge margin; ligament thin, stout, brown, re-enforced below with a nar- 

 row elongate-triangular ossiculum; maximum longitude, 11; altitude, 8; 

 diameter, 6.G; vertical of beaks behind the anterior end, 6 mm . 



Hab. — Station 2791, off the southwest coast of Chili, in 677 fathoms, 

 mud; temperature 37°.9 F. 



This species has the mantle margin simple, the siphons extremely 

 short, retracted by the septal muscles ; the ova project into the anal 

 chamber from the surface of the visceral mass in rounded lobules, much 

 as in Myonera ; a number of the dehiscent ova were retained in the anal 

 chamber. There were four septal orifices on each side ; their apertures 

 simple, oval and oblique; the septum was rather muscular, but not sol- 

 idly so as in Cuspidaria ; its surface was heaped up iu sundry wave-like 

 prominences behind and on each side of the foot. The palpi were ex- 

 tremely small, the lower ones nearly absent ; the foot was short, stout, 

 and subcorneal; the anal chamber quite small. 



