CLASS PELECYPODA 
215 
Genus XYLOPHAGA Turton, 1822. 
Shell globular, with a transverse furrow; gaping in front, closed behind; 
pedal processes short and curved; anterior margins reflected, covered by 
two small accessory valves; burrow oval, lined with shell. (Tryon. S. S. 
Conch.) 
Type. Xylophaga dorsalis Turton. 
Distribution. Norway, Britain, Western North and South America, 
Mergive Island. Bores an inch deep, and across the grain, in floating 
wood and timbers which are always covered by the sea. 
Range in time. Tertiary. 
Xylophaga mexicana Dali, 1908. 
Bull . Mus. Comp. Zool., 43 :425. 
Shell small, short, posterior area rounded behind, concentrically 
marked only with incremental lines; median furrow wide, channelled, in 
the adult bounded behind by a flattened thread; in front the elevated 
margin of the channel is obliquely serrate by the termination of the 
sagittate sculpture of the anterior area, which a little more anteriorly 
becomes very fine, so as to require strong magnification to bring out its 
character; anterior margin of the valves with a rectangular sulcus, from 
whose apex an impressed line proceeds to the umbo, the angulation of the 
sculpture resting on this line; anterior auriculation small; anterior dorsal 
margin strongly reflexed; interior smooth except for a strong, flattish 
rib which extends from the umbo under the middle of the wider external 
channel; umbo much incurved; myophore small and slender. Length, 4.2; 
height, 5.2; diameter, 4 mm. (Dali.) 
Type in U. S. N. M. Type locality, U. S. S. “Albatross,” Station 
3422, off Acapulco, Mexico, in 141 fathoms. 
Range. Monterey, California, to Acapulco, Mexico. 
Xylophaga californica Bartsch, 1921. 
Proc. Biol. Soc. Wash., 34:32. 
In Xylophaga californica there are about 14 denticulated ridges to a 
millimeter in the center of the posterior area, and the denticulated ridge 
bearing posterior median portion is .7 mm. in width at the angle of junction 
of the posterior with the median part. Type measures, length, 4.9; alti¬ 
tude, 4.7 mm. (Bartsch.) 
Type in U. S. N. M., No. 209876. Type locality, Pt. Pinos Light, 
California, U. S. S. Albatross Station 4525. 
Range. California. 
