Description of the Fossils in the older Deposits of the Rhenish Provinces. 359 



Trochus Ivanii, Lev., Mem. de la Soc. Geol. de France, t.ii. PI. II. f.24.. Var. Tab. nost, XXXII. f. 16. 



We have represented this variety, which we should have regarded as a distinct species, if intermediate 

 forms had not obliged us to refer it to the TV. Ivanii from Tournay, which is itself extremely variable 

 in that locality. Our variety is much more depressed than the type of the species and the rounded volu- 

 tions scarcely present a rudiment of the area and the keel. The striae are more unequal and at less 

 regular distances : the base of the shell also is less inflated and the aperture is more rounded. 



Paffrath ; rare. Tournay (Belgium), in the mountain limestone. 



1. Pleurotomaria catenulata, nob., Tab. nost., XXXII. f. 17, \1 a. 



Shell in the form of an abbreviated cone, composed of four convex volutions flattened on the upper 

 part. Suture simple. Volutions ornamented with six or seven granular threads, of which the two 

 central are the largest and form a distinct angle upon that part of the spire. The space between 

 these two threads is occupied by concave striae representing the fissure of the right lip. Base of 

 the last volution wide, convex, covered with very numerous and very regular concentric striae, 

 between which there is often one very fine intermediate. Umbilicus very small. Aperture trans- 

 verse. Left lip slightly arcuated. Columella salient. Inferior edge parallel to the superior. Right 

 lip rather angular toward the middle part where the notch is. 



This species is apparently allied to P. aspera (J. Sow., Geol. Trans., Second Series, Vol. V. PI. LIV. 

 f. 16.; Phill. Pal. Foss. XXXVII. f. 177.), but the ridges are less distinct and the striae are not strictly 

 granulated. 



Villmar ; common. 



2. Pkurotomaria Orbignyana, nob.. Tab. nost., XXXII. f. 18, 18 a. Var. a, f. 19, 19 a. Var. b, f. 20, 



20 a. 



Shell conoidal, pointed at its summit and enlarged at its base, with six rounded volutions, ornamented 

 with six equally spaced transverse threads obliquely traversed by lamellar folds inclined backward 

 and forming an elegant chequer work on the surface of the shell. Upon the last volution these strisB 

 terminate at a narrow channel which limits its base, and in which are seen striae, the concavity of 

 which is turned forward. Beyond this, very delicate, concentric threads, sometimes unequal, like 

 those of the upper part of the volutions, are traversed by lines of growth again directed backward 

 and converging toward the umbilicus. Suture canaliculated, in consequence of the junction of the 

 volutions below the channel. Aperture subquadrangular. Columella a little elongated and arcuated. 

 Right lip with a narrow fissure which corresponds to the external channel. Height, 10 millim.; 

 diam. of the base, 9. 



Var. a. (fig. 19, 19a.) Transverse threads less salient; oblique folds less close-set and rounded. 



Var. b. (fig. 20, 20 a.) Transverse threads very distinct ; oblique lamellae also very prominent ; and 

 all the volutions angular. 



This shell has some analogy with the Euomphalus granulatus, Miinst., Beitrage, iii. Heft, PI. XV. 

 f. 10. 



The figure of Pleur. cancellata, Phill. Palaeoz. Foss. XXXVII. f. 1 76, is too imperfect to enable us to 

 decide if this species does not belong to one of our varieties. 



Villmar ; very common. 



3. Pleurotomaria Lonsdalii, nob.. Tab. nost., XXXII. f. 21, 21 a. 



Shell in form of an abbreviated cone, composed of five volutions, ornamented with transverse granular 

 threads, four in number, and between which are intercalated more delicate striae. Upon the base 



3 a2 



