loo Bulletin 39 373 



Genus SCAPHELLA Swainson 



Scaplielfia costaricana,n. sp. Plate 15, figure 13 



Type fragmentary consisting of the nucleus and part of the 

 three succeeding whorls; the shell is subfusiform; nucleus large, 

 smooth and mammilate at its apex; the three following whorls 

 are slightly contracted about the upper sutures and strongly sculp- 

 tured with coarse subregular, spiral threads separated by inter- 

 spaces as wide or a little more ; the spiral threads and their in- 

 terspaces are crossed by fine lines of growth; sutures distinct; the 

 columella with four plaits, the posterior one being the strong- 

 est. 



Length 29, diameter iS, diameter of nucleus 5.75 mm. 



The unique type is unfortunately fragmentary and consists 

 of the large, smooth, mammilate nucleus and part of the 3 suc- 

 ceeding whorls. The shell is subfusiform and the whole surface 

 is strongly sculptured with coarse, spiral threads. The columel- 

 la is provided with 4 strong plaits. The type specimen was found 

 in the Dentalium zone of the Upper Uscari shales of Codes 

 Creek. 



Uscari Stage: Codes Creek. 



Genus IVIITRA Lamarck 



Mitra Swainson! Broderip, var. Simonensss, n. var. Plate 6, fig. i. 



cf. Mitra Swainsoni Roderip, 1835, Proc. Zool. Soc. , p. 193. 



cf. Mitra Swainsoni Reeve, Conch. Icon., Mitra, pi. i, fig. 4. 



cf. Mitra Swainsoni, var. antiltetisis Dall, 1S89, Bull. Mus. Comp. 

 Zool., vol. 18, p. 1.58, pi. 38, fig. 7. 



Shell large, of about 6+ v\^horls; the spire whorls are slight- 

 ly convex, the last distinctly shouldered above, depressed or 

 slightly concave about its middle; sculpture consisting on the 

 spire-whorls of about 6, heavy, spirals cords with sculptured 

 interspace as seen on Mitra Henekeni and longa; on the later 

 v/horls the spiral cords become more widely spaced and on the 



