8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



KEY TO THE PYRAMIDELLIDAE WITH TRIPLICATE COLUMELLA 



Axial ribs present. 



Spiral cords present Triptychus 



Spiral cords absent (Pharcidella) 



Axial ribs absent Longchacus 



Genus TRIPTYCHUS Morch 



1875. Triptychus Morch, Malak. Blatter, vol. 22, p. 158. 



Shell elongate-conic, not umbilicate, having three columellar folds, 

 with axial ribs which are rendered nodulose by the spiral cord on 

 each whorl and a peripheral cord. Base provided with a strong median 

 spiral cord and a lesser, more oblique fold anterior to this ; the basal 

 cords are rendered nodulose by the continuation of the axial ribs; 

 outer lip with internal spiral folds. 



Type: Triptychus niveus Morch, 



TRIPTYCHUS PLIOCENA, new species 

 Plate I, figure i 



Shell elongate-conic, rather stout. The nucleus consists of about 

 2^ inflated, strongly rounded whorls, which form a rather elevated 

 spire, whose axis is at right angles to that of the postnuclear turns, 

 in the first of which the nucleus is about one-third immersed. The 

 postnuclear whorls are well rounded and provided with strong spiral 

 cords, of which two are present on the first whorl and three on the 

 rest. The first of these cords is at the summit, and the other two 

 divide the space between this and the peripheral cord in equal spaces. 

 In addition to these spiral cords the whorls are marked by axial ribs, 

 which equal the spiral cords in strength and render these nodulose 

 at their junction. The axial ribs extend over the periphery of the last 

 whorl and the base, becoming somewhat weaker on the base. Of the 

 axial ribs i8 are present on the last whorl. Suture strongly con- 

 stricted. Periphery provided with a spiral cord equaling those pos- 

 terior to it. Base slightly concave, provided with a strong median 

 spiral cord and a weak, more oblique, anterior cord, both of which 

 are nodulose. Aperture obliquely oval, columella provided with three 

 weak folds, of which the posterior is the stronger ; outer lip reinforced 

 by four spiral cords within. 



The type, U.S.N.M. No. 561595 (Locklin No. 1419 C/D), comes 

 from the Pliocene deposits of North St. Petersburg, Fla. It has the 

 nucleus and 6.1 postnuclear whorls and measures: length 4.5 mm.; 

 diameter 1.5 mm. U.S.N.M. No. 561596 contains three additional 



