MONOGRAPH OF AMERICAN SHIPWORMS. 7 



Terminal portion of tlie blade not cupped. 



Terminal portion of the blade ending in a forked tip 



Lyrodus. 

 Terminal portion of the blade not ending in a forked tip. 

 Terminal portion ending in a calcified ^nob—Teredops. 

 Pallets not paddle-shaped. 

 Pallets spoon-shaped. 



Terminal portion of the blade cupped Neoteredo. 



Terminal portion of the blade not cupped. 



Auricle projecting as a shelf over the posterior me- 

 dian portion of the inside Teredora. 



Auricle not projecting as a shelf over the posterioi 

 median portion of the inside. 



Auricle fused with the posterior median portion 

 on the inside Psiloteredo. 



Genus BANKIA Gray. 



1840. Bankia Gray, Synop. British Mus., p. 76. 



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. 



Type. — Teredo hipalmuJata Lamarck. 



Subgenus Bankia Gray. 



1840. Bankia. Gray, Synop. British Mus., p. 76. 

 In this subgenus the distal end of the cones terminates in a thin 

 xiembrane, which is fimbriated at the free margin. The lateral 

 iimbriations form long awnlike projections. 

 Type. — Teredo hlpdlTnulata Lamarck. 



BANKIA (BANKIA) SETACEA Tryon. 

 NORTHWEST SHIPWOBM. 



Plates 4, 5, and 30, fig. 3. 



1863. Xijlotrija setacea Tryon, Proc. Acad. Nat. Sci. Philadelphia, ser. 2, 

 vol. 7, pp. 144, 145, pi. 1, figs. 2, 3. 

 ohell very large, subglobose, 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 riblike 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 ; that is, the part nearest the umbone, than on the later, be- 

 coming successively closer spaced as the shell advances in age. In 

 the early portion they are about twice as wide as the ridges, while In 



