256 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxm. 



the posterior row is less strongly developed than the anterior and is 

 brown in color, while the channel that separates it from the anterior 

 and the anterior row are yellowish white. From the third whorl on 

 the posterior row of tubercles becomes more strongly developed than 

 the other. Beginning with the fourth turn, a slender tubercular keel 

 appears in the space between the two tubercular ridges, which on the 

 sixth turn is as strong as the anterior cord. Thus the shell is marked 

 by a brown tubercular ridge at the summit and two white tubercular 

 ridges anterior to it after the fourth turn. The tubercles are joined by 

 a broad spiral cord and axial riblets. The connections inclose quite 

 deep oblong pits. There are eighteen tubercles upon the first whorl, 

 twenty-two upon the fifth, and t-^enty-f our upon the penultimate 

 turn. Sutures channelled. Periphery of the last whorl strongly 

 angulated, marked by a low subacute keel. The channel between 

 the peripheral keel and the supraperipheral row of tubercles is crossed 

 by weak extensions of the axial riblets. Base short, hght brown, 

 having a single slender, spiral thread, about as far anterior to the 

 periphery as the suprasutural tuberculated ridge is posterior to it. 

 There are also very slender extensions of the axial riblets, which 

 pass from the periphery to the insertion of the columella. In addi- 

 tion to the above sculpture, the base is marked by many exceedingly 

 fine spiral striations and lines of growth. Aperture subquadrate; 

 posterior angle obtuse, strongly channelled anteriorly, outer lip 

 rendered sinuous by the external sculpture. Columella short, thick, 

 and somewhat curved, covered by a faint callus which also extends 

 over the parietal wall. 



The type is an immature specimen which has lost the nucleus. 

 The eight remaining whorls measure: Length, 3.7 mm.; diameter, 

 1.6 mm. It is Cat. No. 4069, U.S.N.M., and was collected at Cape 

 vSt. Lucas, Lower California. Another badly worn individual. Cat. 

 No. 15434, U.S.N.M., is from Guacomayo, Mexico. 



TRIPHORIS PANAMENSIS, new species. 



Plate XVI, fig. 19. 



Shell sinistral, elongate conic, of dark-brown color. Nuclear 

 whorls tliree, forming a cylindrical, smooth apex. The five succeed- 

 ing turns are marked by a double spiral row of tubercles, which are 

 separated by a channel considerably wider than the channeled 

 sutures. Beginning with the eighth turn a tuberculate cord makes 

 its appearance in the space between the two tubercular ridges, a Httle 

 nearer to the one at the summit than the supraperipheral one. This 

 cord, at first faintly developed, increases steadily in size, until on the 

 last volution it almost equals the other two in strength. The tuber- 

 cles occur in regular axial series and are connected spirally and axially 

 by slender riblets, the riblets inclosing small squarish m.eshes. There 



