MONOGRAPH OF AMERICAN SHIPWORMS. 9 



Subgenus Neobankia Bartsch. 



1921 Neobankia Bartsch, Proc. Biol. Soc. Washington, vol. 34, p. 26. 

 In Neobankia the pallets consist of cone-in-cone elements, covered 

 by a thin membrane, which is denticulate at the free margin. 

 Type. — Bankia {Neobankia) zeteki Bartsch. 



BANKIA (NEOBANKIA) ZETEKI Bartsch. 

 ZETEK SniPWOEM. 



Plates 6, 7, and 30, fig. 1. 



1921, Bankia {Neobankia) zeteki Bartsch, Proc. Biol. Soc. Washington, 

 vol. 34, pp. 26-27. 



Shell subglobular, white, the extreme anterior portion with the 

 usual sinus and reflected smooth callus at its external border, the 

 main portion bearing the dental ridges, which radiate from the an- 

 terior margin, where they are closely crowded, backward to the junc- 

 tion with the posterior median portion. Here they are separated by 

 spaces about twice as wide as the ridges. These ridges are finely 

 denticulated at their free margin. Seventy of these ridges are ap- 

 parent, but at least 20 more appear to have been eroded at the umbo- 

 nal end. The anterior median area is rather broad, and bears the 

 closely crowded, strongly denticulated ridges, which are separated 

 by mere lines. These ridges terminate in a straight line posteriorly. 

 The middle portion of the median part is marked by the usual groove 

 that extends from the umbones to the basal margin, and this groove 

 is crossed by strong lines of growth, which extend over the posterior 

 median part. The posterior part forms a strong auricle, which is 

 conspicuously separated from the posterior median portion, the shell 

 here bending strongly inward. The auricle is marked by more or 

 less curved lines of growth, which give one the false impression of 

 raised cords. The interior of the shell is bluish white. The umbone 

 projects inward as a strong knob, and the blade springs from deep 

 within the umbone, and makes a decided curve, the early portion 

 having the broad side of the blade parallel to the inner surface of the 

 shell, that is within the umbones, while within the median portion of 

 the shell the blade becomes twisted, so that it assumes an oblique 

 position to the inner surface of the shell. The suture of the anterior 

 and the median portion is marked by a slightly tumid area. The 

 middle median portion is decidedly roughened and bears the usual 

 laiob at the ventral margin. The auricle extends over the median 

 portion on the inside as a strong shelf. The inside of the auricle 

 shows the same translucent cordlike lines apparent on the exterior. 

 The pallets are of the cone-in-cone-shape variety, the individual cones 

 being semicircular in cross section, the inner free border being 

 straight, while the outer is curved. The cone elements are rather 



