106 J. Starkie Gardner — Cretaceous Gasteropoda. 



and sharp as in the recent species, but have more the appearance of 

 folds. In some of the larger specimens the ribs disappear altogether 

 on the last three or four whorls, and are represented only by more or 

 less strongly marked lines (Plate lY. Fig. 1). The striae are fine and 

 numerous (Plate IV. Fig. la), fifty or sixty on each whorl. The 

 sutures are \qvj distinct, the margins of the whorls being usually 

 raised into a roll -like collar. This collar appears on the last whorl 

 in the form of a conspicuous spiral keel, against which the ribs term- 

 inate, leaving the base of the whorl, which is very flat, marked 

 with strigs and lines of growth only. The aperture is oval or quad- 

 rate, and in the perfect state was probably terminated anteriorly in a 

 sort of beak (Plate IV. Figs. 2 and 3) ; lips thin ; columella smooth. 

 The cast of the shell generally preserves the rib marks, except near 

 the apex, where the whorls are smooth and very rounded. 



This and Scalaria Dupiniana are the most characteristic and easily 

 recognized of the Cretaceous Scalarise. It was first described and 

 figured by Michelin as Melanojpsis Clementina in 1833 ; redescribed 

 by d'Orbigny as Scalaria, and figured in the Pal. FranQ., 1842 ; 

 figured by Chenu in the Man. de Conchy liologie, and by Pict. & Camp.. 

 Terr. Cret. The species is very distinct, and there are fortunately no 

 synonyms. It is mentioned by many authors from numerous locali- 

 ties in France and Switzerland, etc., and it must be considered to 

 have had a wide rang-e. 



I have had an opportunity of examining the original of d'Orbigny's 

 figure in the Pal. Frang. at the Ecole des Mines, and find that the 

 drawing represents the whorls more convex and inflated than they 

 actually are, and the aperture is a restoration. Dr. Chenu's figure is 

 copied from this engraving. Pictet's figure is more truthful, but is 

 taken from a very indifferent specimen. 



This species departs in its character perhaps more widely than any 

 other, from the typical Scalariee, and also presents a peculiar instance 

 of the power of the animal to secrete the ornamentation of its shell 

 becoming enfeebled with age. 



This species is essentially characteristic of the Gault, and is found 

 at Folkestone, Lyme Eegis, etc. The figured specimens are in m.j 

 collection. 



So. Dupiniana, d'Orb. Gault. Plate IV. Figs. 5 and 6. 



Shell elongated ; angle 23° to 25°, with fifteen or more rounded 

 and inflated whorls ; ribs coarse, obtuse, fold-like, generally num- 

 bering about twelve, but on the last whorls of larger specimens as 

 many as eighteen, though then less prominent, as if effaced by age. 

 Striae regular, or alternately preponderating, more or less deeply 

 marked and very variable in number, there being from twenty to 

 thirty on corresponding whorls of equal-sized specimens (Plate IV. 

 Figs. 5a, 56) . The spiral keel appears on the last whorl, against which 

 the ribbing abruptly terminates. This keel is represented in the 

 spire by a smooth sutural region, which is, however, sometimes 

 overlapped. The basal or columellar region is marked by concentric 

 striae and by lines of growth. The mouth appears to have been 



