Description of the Fossils in the older Deposits of the Rhenish Provinces. 365 



surrounded. The inverse arrangement of the strige above and beneath shows that it must have been 

 formed by the simultaneous secretion from the two contiguous edges of a fissure in the mantle of the 

 animal, a circumstance analogous to that which occurs in var. a. of Murchisonia angulata and in Pleu- 

 rotomaria Defrancii*. We have therefore placed this shell in the genus Schizostoma, to which also 

 E. elatus, of Hisinger (PI. XI. f. 7), ought to be referred. This latter has a similarly striated keel. 

 Eifel ; Newton. 



2. Schizostoma Puzosii, nob., Tab. nost., XXXIV. f. 8, 8 a, 8 b. 



Shell discoidal, planorbular, formed of six volutions flattened above and convex beneath. Suture 

 wide and channelled. Volutions ornamented at their middle part with eight or ten transverse, 

 undulated and unequally separated striae, which are crossed upon the first volutions by longitudinal 

 lines. These latter, at first simple and straight at setting oflT from the canal of the suture, soon 

 become divided into two or three as they approach the lower edge. The latter is formed of two 

 equal keels which separate a shallow decurrent channel. Setting off from the upper keel the strise 

 go forward again to reach the suture ; at length upon the last volution they turn backward and run 

 toward the umbilicus after having made still one or two more wide undulations. On the base of 

 the shell there are two bands of concentric striae separated by a zone which is destitute of striee, as 

 well as the part surrounding the umbilicus where there are only striae of growth and obsolete folds. 

 Umbilicus funnel-shaped, showing a part of the spire within. Aperture transverse, with a sinuous 

 edge, and disunited above, rounded beneath and straight above. External angle of the lip straight, 

 furnished with a shallow notch corresponding to the upper keel. Aperture equal to two-fifths of 

 the diameter of the shell. 



We are indebted to M. Puzos, to whom we have dedicated it, for the knowledge of this fine shell. 



Eifel ; very rare. 



1. Cirrus Leonhardi, nob.. Tab. nost., XXXIV. f. 9, 9 a. 



Shell of a short conical form, pointed at the summit, very wide at the base, and composed of seven 

 angular volutions. Suture wide and deeply channelled. The first volutions have two simple keels, 

 which upon the following are loaded with transversely compressed tubercles, almost contiguous, 

 and increasing in size. Upon the last volution a third keel, also nodulose, forms a continuation to 

 the suture. Lastly, the umbilicus is surrounded by a varix which divides the base of the shell into 

 two parts. Upon the last volution lines of growth, very distinct, irregular, and much undulated, 

 pass over the folds of each keel and take an oblique direction toward the umbilicus. This latter is 

 ieep and funnel-shaped, and shows a part of the spire within. Aperture entire, subpentagonal, its 

 edges joined and undulated, nearly equal to half the total diameter of the shell. 



Paff"rath ; rare. 



2. Cirrus rotundatus, Sow. PI. CCCCXXIX. f. 1, 2. 



A smaller and more conoidal variety. 

 Paffrath. 



Roiella heliciformis, Goldf. Bonn Mus. Helicites helicincBformis, Schlot., Petref., PI. XI. f. 6. 

 Paffrath ; common. 



* For an explanation of the mode of closing the fissure in these various genera see Bull, de la Soc. 

 Geol. de France, vol. xii. p. 157, note. 



VOL. VI. SECOND SERIES. 3 B 



