216 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Xylophaga washingtona Bartsch, 1921. 
Proc. Biol. Soc. Wash., 34:32. 
In X. washingtona there are about ten denticulated ridges to a milli¬ 
meter in the center of the posterior area, and the denticulated ridge bearing 
posterior median portion is 1.2 mm. in width at the angle of junction of 
the posterior with the median part. Type measures, length, 5.7 ; altitude, 
5.5 mm. (Bartsch.) 
Type in U. S'. N. M., No. 344479. Type locality, San Juan Island, 
Washington. 
Range. Puget Sound, Departure Bay, British Columbia, and off 
Oregon and Washington coasts. 
Family TEREDID2E. 
Genus BANKIA Gray, 1840. 
The genus is characterized by having the pallets consisting of a series 
of cone-in-cone structures, which give to them the appearance of an ear 
of wheat. (Bartsch.) 
Type. Teredo bipalmulata Lamarck. 
Distribution. Universal. 
Range in time. Found in fossil woods in the green sand of England. 
Subgenus Bankia Gray. 
Bankia setacea Tryon, 1863. 
Proc. Acad. Nat. Sci. Phita., p. 144; pi. 1, figs. 2, 3. Bartsch, U. S. N. M. Bull., 122:7- 
pis. 4, 5, and 30, fig. 3. 
Shell very large, sub-globose, white, excepting the anterior median 
portion, which has a rosy flush, a faint suffusion of which also extends over 
the anterior part. The anterior part has a strong sinus at the extreme 
anterior margin, which is covered with a thick callus that is reflected 
partly over the exterior, where it forms a pronounced crest. The anterior 
part is marked by strong rib-like dental ridges which expand slightly 
fan-shaped from the anterior margin to the posterior termination; forty- 
three of these ridges occur on the specimen figured. These ridges are 
more distantly spaced on the early parts of the shell (the part nearest the 
umbo) than on the latter, becoming successively closer-spaced as the shell 
advances in age. In the early portion they are about twice as wide as the 
ridges, while in the latter part they are scarcely as wide as the ridges. The 
spaces between the ridges are marked by fine striations which coincide 
with the ridges. These markings are best shown on the younger portions 
of the shell. The ridges have their margins minutely denticulated. In 
cross section they would appear triangular, with the dorsal side about 
