Description of the Fossils in the older Deposits of the Rhenish Provinces. 357 



Shell usually rather short, mucronated at the summit, and inflated toward the middle. Volutions 

 slightly convex, rounded or slightly flattened. Varix very slight, sometimes none. Keel scarcely 

 visible, but always indicated by the two threads which accompany it. Striae of growth similar to 

 those of the preceding species. Base of the last volution simple. Aperture oblong, oblique, con- 

 tracted at its extremity. Columellar lip covered with a callosity which rises to the upper angle of 

 the aperture, where it is united to the right lip, forming a little channel within. Columella twisted, 

 recurved in the form of an elongated S. Canal short and very shallow. Right lip thin, furnished with 

 a deep slit which corresponds to the keel. Height, 39 millim. ; diameter of the last volution, 17. 



Var. a. Shell shorter and conoidal. 



Paffrath &c. ; with the preceding, common. Gronau. 



There is found in the limestone of Nehou (La Manche) a second, more slender variety, with rounded and 

 very convex volutions. We have also collected it at Ize, near Vitre (Dep. de I'lle et Vilaine). 



The four species which we have just described are connected together by numerous varieties, and cha- 

 racterize the principal type that we have distinguished. We have rather proposed to facilitate the study 

 and the knowledge of these numerous shells, than to establish among them really distinct species. 



5. Murchisonia bigranulosa, nob., Tab. nost., XXXII. f. 9. Var. a, f. 10. M. bilineata, Phil. Pal. Foss., 

 XXXIX. f. 191. Var. 5, f. 11. 



Shell conoidal, turriculated, composed of from ten to twelve flattened volutions. Keel salient, forming 

 a little band divided by a more or less distinct line and occupying the middle of the volutions. Two 

 rows of granulations accompany the suture, the one above, the other below. Upon each volu- 

 tion the elongated and ovoid granulations of the upper row, sixteen or seventeen in number, are 

 double the size of those of the inferior row. Suture deep and channeled. Base of the last volution 

 (in the variety b, fig. 11), covered with granular lines formed by the crossing of the transverse striae 

 and folds which radiate from the base of the left lip : these latter end at the inferior row of tuber- 

 cles. Lines of growth, moreover, cover the whole shell. They turn abruptly backward as they 

 approach the keel, and then forward again when they have crossed over it. Aperture elongated, 

 contracted at its extremity. Left lip nearly straight. Columella a little elongated. Canal very 

 short, at the union of the two lips. Right lip furnished with a pretty deep slit, the successive filling 

 up of which during the growth of the shell is marked by the median keel. 



Height, 80 millim. ; diameter of the last volution, 24. 



Var. a. Shell shorter and more conoidal than the preceding. On the last volution the lower row of granu- 

 lations is sometimes represented by a ridge or a simple keel, and then the upper volutions have only a 

 single row of granulations. We refer to this variety the Turritellu abbreviata (Min. Conch., PI. DLXV. 

 f. 2. Syn. Murch. bilineata, Phill. Pal. Fos., PI. XXXIX. f. 191), which, according to the author, 

 has two rows of granulations upon each volution. In our opinion, therefore, Bronn was mistaken in 

 referring it to one of our preceding species. Still, it must be acknowledged that this variety is very 

 near to the abbreviated variety of M. coronata, although there is a great difference between the ex- 

 tremities of these two species. 



Paffrath ; very rare. Devonshire, for the variety a. 



6. Murchisonia binodosa, nob.. Tab. nost., XXXII. f. 12. 



Shell conoidal, subturriculated, composed of from eight to ten deeply excavated volutions. A rather 

 wide, very flat, but neatly limited little band occupies the centre of each volution. Two rows of 

 tubercles accompany the suture. The tubercles of the upper row, sixteen in number, are very sa- 

 lient and rounded. Those of the lower row, on the contrary, are but slightly evident, being well 

 seen only on the last volutions. Lines of growth fine and undulated, turning backward as they ap- 

 VOL. VI. SECOND SERIES. 3 A 



