Description of the Fossils in the older Deposits of the Rhenish Provinces. 371 



is found in the mountain limestone of Belgium, Ireland, Yorkshire and Derbyshire ; wherefore, notwith- 

 standing the great difference of its stature, we can only give it as a variety. When the shell is not de- 

 composed, which happens rarely, extremely fine radiating striae may be seen, crossed by the lines of 

 growth. The shell, when partly decomposed, is of a more or less silvery dull white. 

 Paffrath ; very common. 



8. Spirifer resupinatus, Terebratulithes vestitus, Schlot. Petrefact., PI. XV. f, 1 . 



The specimens collected at Mettmann near Elbersfield in the Strygocephalus limestone, are identical 

 with those of the mountain limestone : but those of the Eifel differ somewhat, and come nearer to Tei-e- 

 bratulithes striatulus, Schlot., PI. XV. f. 4. 



Mettmann and mountain limestone of Vise. 



9. Spirifer connivens, Phill. Geol. of Yorksh., Part ii. PI. XL f. 2. 



Very small triangular Spiriferi are found at Paffrath, similar to <S^. connivens. This species is very 

 common in the mountain limestone of Yorkshire, and we have also found it at Boulogne. It appears to 

 us to be only a variety of the preceding species. The specimens from Paffrath are distinguished merely 

 by eight or ten rather more distinct radiating strias. 



The Spiriferi of the family of Impressi of de Buch, that is to say, the Sp. ( Terehratulitltes) striatu- 

 lus, Sp. (T.y similis, Sp. (T.) excisus, Sp. (T.) vestitus, Schlot., Sp. (T.) resupinatus, Mart., and Sp. 

 connivens of Phill., are very much like each other, and might be considered as varieties of the same 

 species. Their specific differences, if any exist, appear to us at least very difficult to ascertain. It is 

 natural enough that this species, being ill-defined and subject to numerous varieties, should be found in 

 beds of very different ages. 



Leptana sericea, Sow. Sil. Syst., PI. XIX. f. 2. 



This very finely striated shell is found at Braubach. 



1 . Orthis Murchisoni, nob., Tab. nost., XXXVI. f. 2. 



Upper valve forming rather more than a half-circle, flat above, folding back below toward the edges, 

 and ornamented with nineteen radiating ribs, sharp-edged near the beak, and slightly inflected upon the 

 sides. These ribs curve toward the front and follow the form of the valve. They are very finely striated, 

 and the striae as they bifurcate become more and more numerous on approaching the edges, where 

 fifteen may be reckoned upon each rib. Ribs wide, flattened, and having a tendency to disappear near 

 the lateral edges. Hinge straight. Beak forming a scarcely evident prominence above the cardinal 

 line. Lateral edges uniting to the hinge at an angle of 85°. Ventral valve unknown. 



A fossil collected by the late Rev. J. J. Conybeare, on Snowdon in Wales, and figured at PI. XXV. 

 f. 2, in the Fourth Vol. (1st Series) of the Trans, of the Geol. Soc. of London, appears to be nearly 

 similar to this species. 



Siegen, grauwacke; rare. 



2. Orthis Sedgwicki, nob., Tab. nost., XXXVI. f. 1. 



Ventral valve forming rather more than a half-circle. Hinge straight, without area. From the beak, 

 which touches the cardinal line without any prominence, set off twenty folds, which soon bifurcate, to 

 become more and more subdivided as they approach the edges, where they are only represented by 

 bundles of finely striated folds. Dorsal valve unknown. 



The Orthis Sedgwicki is related to O. Murchisoni, and this affinity is naturally expressed by the ap- 

 proximation of two celebrated names, as intimately united by the noble friendship of those who bear 

 them as by the unity of their labours. 



Grauwacke of Landerskron and Siegen ; rare. 



