MONOGRAPH OF AMERICAN SHIPWORMS. 15 



the calcareous deposit are broken away a series of laminae within 

 laminae or condensed cone-in-cone-shaped elements appear. The 

 inside has a solid expanded portion at the base, and beyond this a 

 series of laminae, separated by spaces about as broad as the laminae 

 or a little wider. 



The type, Cat. No. 207695. U.S.N.M., was collected by Dr. Robert 

 E. Coker in the Estero del Palo Santo, Tumbes, Peru, in a green 

 mangrove root. 



It measures: Height, 20 mm.; length, 20 mm.; diameter, 18 mm. 

 The pallet measures: Length, 41.5 mm., of which 21 mm. belong to 

 the stalk; the greatest diameter is 5.2 mm. 



This is the largest shipworm in American waters, and it is not 

 only remarkable for its size, but for its infesting living mangrove 

 wood, sujDposed to be immune to the attack of shipworms. 



BANKIA (NAUSITORA) BRAZILIENSIS, new species. 

 BRAZIL SHIIMVORJW. 



Plate 20, fig. 3 ; plate 31, fig. 1. 



Shell subglobular. of moderate size, flesh colored. The anterior 

 part marked by the usual sinus, Avith a smooth, thin callus slightly 

 reflected over the exterior surface. From this the dental ridges 

 radiate backward in a fan-shaped manner. They are separated by 

 spaces about one and a half times as wide as the ridges. The ridges 

 slope a little more abruptly on the umbonal side than the ventral side, 

 and are finely denticulated on their free margin. The umbones of 

 the type are partially eroded, but there are 49 ridges present in the 

 type. The line of junction betAveen the anterior and the anterior me- 

 dian portion is well marked and slightly sinuous. The anterior me- 

 dian portion is rather broad and marked by strongly* denticulated 

 ridges which are separated by very narrow lines and which join the 

 dental ridges of the anterior part at a little more than a right angle. 

 The anterior half of the middle median portion is slightly convex, 

 and rendered rough by the feeble nondenticulated subobsolete con- 

 tinuation of the dental ridges while the posterior portion is slightly 

 concave. The posterior median portion is about as wide as the ante- 

 rior and the middle portion of the median part, and is marked by a 

 series of strong lines of growth, which give it a more or less rough- 

 ened aspect. The posterior part forms a narrow auricle which joins 

 the posterior part of the middle portion in an even concaved line. 

 The interior is bluish white. The junction of the anterior and the 

 median portion is marked by a tumid ridge while the posterior part 

 overlaps the median part as a callus. Avhich extends over the median 

 part, at the umbonal half, as a slender shelf. The posterior auricle is 

 thin and marked by a series of opaque and translucent areas when 



