14 BULLETIN 122, UNITED STATES NATIONAL MUSEUM. 



The type measures : Height, 4 mm. ; length, 3.8 mm. ; diameter, 4.5 

 mm. The pallets measure : Length, 7.2 mm., of which 4.5 mm. be- 

 long to the stalk; diameter, 1.6 mm. 



This species is smaller and has finer sculpture even than Bankia 

 {Nausitora) hraziliensis. 



BANKIA (NAUSITORA) DRYAS Dall. 

 DAIL SHIPWOBM. 



Plates 17-19, and plate 31, fiir. 3. 



1909. Xylotrya clryas Dall, Proc. U. S. Xat. Mus., vol. 37, No. 1704, pp. 

 162-174, pi. 25, figs. 2, 3, 5, 6, 7. 

 Shell gigantic, subglobular. Color of the anterior part and the 

 anterior median part pale rose; the rest of the median part flesh 

 colored and the posterior auricle white. The anterior part with the 

 usual sinus and reflected callus, but the callus is separated from the 

 dental bearing portion by an impressed sinus. The latter is marked 

 by the dental ridges, Avhich turn upward suddenly at the anterior 

 extremity and then expand fanlike backward. These ridges are as 

 wide or a little wider than the spaces that separate them. The 

 umbonal members have been eroded, but there remain 93 in the type. 

 These ridges are finely denticulated at their free margin. The indi- 

 vidual denticles are marked by slender grooves on both sides of the 

 dental ridges. The anterior median part joins the anterior part in 

 a somewliat sinuous line, and this part is covered by dental ridges 

 which join those of the anterior part at a little more than a right 

 angle. These ridges, which are separated by mere lines only, bear 

 very large, broad denticles. The median portion forms a concave 

 groove at its posterior extremity. The anterior portion of the me- 

 dian part is slightly convex and covered by a series of irregularly 

 disposed wrinkles. The posterior portion of the median part is not 

 quite as wide as the anterior portion of the median part and is 

 marked by lines of growth only; The posterior part forms a narrow 

 auricle and is separated from the posterior median portion by a con- 

 cavely impressed groove. Interior white. Umbone with a strong 

 knob, from the basal portion of which the broad, irregular blade ex- 

 tends almost to the basal knob. The anterior portion has a number of 

 irregular ridges and the suture between the anterior and median por- 

 tion is slightly roughened. The middle of the median part is 

 grooved and bears at its base at the ventral margin the usual strong 

 knob. The posterior part is reflected over the median, and fused for 

 its greater part, but the anterior margin of it projects over and into 

 the cavity of the shell as a shelf, leaving a broad space behind it. 

 Pallet fan-shaped. Stalk very long, cylindric. Blade expanded, 

 featherlike, the outside covered with a thick calcareous deposit, over 

 which a dark periostracum is placed. Where the periostracum and 



