16 BULLETIN 122, UNITED STATES NATIONAL MUSEUM. 



viewed by transmitted light. The pallet has a long stalk. The base of 

 the pallet is solid. The distal half consists of cone-in-cone elements 

 which are covered by a thin calcareous deposit over which a strong 

 periostraciim is stretched on the outside. The inside of the solid por- 

 tion is slightly concave, the distal portion on the inside being marked 

 by a series of cross lines marking the condensed cone-in-cone elements 

 and periostracum. 



The type, Cat. No. 110435, U.S.N.M., was collected by Dr. H. von 

 Ihering at Santos, Brazil. 



It measures: Height, 6 mm.; length, 5.8 mm.; diameter, 5.5 mm. 

 The pallet measures : Length, 8 mm. ; length of stalk, 5.7 mm. ; diam- 

 eter, 2.3 mm. 



This species resembles Bankia (Nausitora) fusticula Jeffreys, but 

 differs from this in having the dental tidges of both the anterior and 

 the anterior median portion much more closely spaced and much 

 finer and more numerous than in Bankia {Nausitora) fusticula 

 Jeffreys. 



BANKIA (NAUSITORA) FUSTICULA Jeffreys. 

 JEFFREYS SHIPWORM. 



Plate 20, fig. 2 ; plate 31, fig. 2. 

 1860. Teredo fusticulus Jeffreys, Ann. Mag. Nat. Hist., ser. 3, vol. 6, p. 12.5. 



Shell small, subglobular. The anterior part and the posterior 

 median jDortion pale brown, the rest white. The extreme anterior 

 portion forms a sinus from which a thin callus is reflected over the 

 anterior dental ridge-bearing portion. The dental ridges radiate 

 from the anterior smooth area backward, spreading out more or less 

 fan shaped, the spaces between the ridges becoming wider toward 

 their distal ends, where they are about two and a half or three times 

 as wide as the dental ridges. The dental ridges are very finely dentic- 

 ulated at their free margin. Thirty-six of these ridges can be 

 counted in the specimen figured, but as usual some of the earlier 

 ones have been eroded at the umbone. The dental ridges on* the 

 anterior median portion correspond with those on the anterior por- 

 tion and meet these in a straight line, which extends from the ventral 

 margin to the umbones. These ridges are closely crowded, being 

 separated by mere impressed lines only, and are marked by strong 

 denticles which are also separated by very narrow lines. The middle 

 median region is a narrow, slightly depressed area crossed by the 

 obliquely curving enfeebled dental ridges, which here become evan- 

 escent. The posterior median portion is a little wider than the an- 

 terior and middle median portion. It is moderately curved and 

 marked by rather strong incremental lines. The posterior part 

 forms an auricle which is slightly upturned at the outer margin 



