498 PROCEEDINGS OF THE ACADEMY OF [July, 



costal spaces, but almost effaced where they pass over the crests of 

 the axial ribs. The aperture is trapezoidal; columella not plicate, 

 but its lower edge is slightly prominent. 



Length 15, diam. 3.25, length of aperture 3.3 mm. 

 Mount Hope bed. 



While related to T. protexta, this species differs by the convexity 

 of the whorls. 

 Drillia harfordiana var. colonensis n. var. 



The shell resembles Pleurotoma harfordiana Rve. in form, but is 

 very much smaller. The anal fasciole is rather wide, concave, with a 

 single prominent spiral cord near the suture. Below the fasciole 

 there are 'rounded, slightly protractive axial ribs, strongest at the 

 shoulder, rapidly diminishing downwards, and ten in number on the 

 penultimate whorl. They are crossed by rather widely spaced spiral 

 cords, of which three are visible on the penultimate, about a dozen 

 on the last whorl. The cOrds are equally developed on the ribs and 

 in their intervals, and the spaces between them are occupied by very 

 fine spiral striae, especially well developed on the fasciole. The 

 €oloration, though faded, is visible on some specimens. There is a 

 white band at the shoulder and several white lines below, on a tawny 

 ground. Length 12, diam. 5.5 mm.; about 9 whorls. 

 Mount Hope bed. 



An allied recent form from Nicaragua is described below. 

 Drillia harfordiana var. flucki n. v. 



Similar to var. colonensis except in the following details. The 

 axial ribs are much more numerous, seventeen on the penultimate 

 whorl; on the last whorl they diminish very rapidly below the 

 periphery, and the spiral cords are noticeably enlarged and prominent 

 on the summits of the ribs; the 6th and 7th below the shoulder are 

 white. From the shoulder to the suture the surface is buff-white, 

 and the growth strise somewhat lamellar; elsewhere the shell is dark 

 mineral -red (of Ridgway's Color Standards). 



Length 19.3, diam. 8, length of aperture 8.2 mm.; 10 whorls, the 

 tip wanting. 



King's Keys, Nicaragua, recent. Rev. W. H. Fluck. 

 The figure of D. harfordiana Rve. measures, length 27.5, diam. 

 12.5 mm. The habitat of the species was and still is unknown, and 

 it has not been described with sufficient detail; but these Central 

 American forms resemble it in general features and may well be 

 local forms of the same species. 



