Cor relation of the Silurian of Bohemia. 57 



shaded, non-micaceous, fine shales ; in most localities, 

 however, are found hard, gritty, hornstone-like, black 

 shales, especially in the neighborhood of diabases (Karlik, 

 Eeporyje). 



Faunistically, this zone is the richest one, and it is 

 relatively thick enough to be divided into subzones. 

 Besides Rastrites peregrinus, which is everywhere the 

 most common species, the following forms occur : Diplo- 

 graptus modestus Lapw., D. (Glyptograptus) sinuatus 

 Nich., D. (G.) bellulus Tornq., Climacograptus scalaris 

 Lin. (auct.), Cephalograptus folium His., C. cometa Gein., 

 Retiolites (Gladiograptus) perlatus Nich., Monograptus 

 lobiferas M'Coy, M. communis Lapw., M. fimbriatus 

 Nich., M. leptotheca Lapw., M. convolutus His., M. tri- 

 angulatus Harkn., M. distans Port!., and Corynoides sp. 



None of these species appears in the next higher zone. 



c. Zone of Rastrites linnei Barr. — Very fine-grained, 

 fissile shales, almost without mica, mostly of gray-green- 

 ish color ; the graptolites in them have a bright silver-like 

 luster ; the best locality is at Zelkovice, where occur : 

 Diplograptus palmeus Barr., D. ovatus Barr., Monograp- 

 tus beclil Barr., M. clingani Carr. var. hopkinsoni Per., 

 M. halli Barr., M. holmi Per., M. marri Per., M. jaculum 

 Lapw. var. variabilis Per., M. planus Barr., M. proteus 

 Barr., M. runcinatus Lapw., M. turriculatus Barr. var. 

 minor, and Rastrites linnei Barr. 



d: Zone with Monograptus turriculatus Barr. — Sim- 

 ilar hard dark shales, in some localities clayish and of 

 dark brown color. Characteristic graptolites are: 

 Monograptus palmeus Barr. var. tenuis Barr., M. turri- 

 culatus Barr. (typical large form), M. jacidum Lapw., and 

 Retiolites (Plegmatograptus) obesus Lapw. Some grap- 

 tolites of the preceding zone occur sporadically here also, 

 as M. proteus, M. runcinatus and M. marri. 



E^fi — P Hod on Beds. 



The commonest fossils in these beds are Monograpti of 

 the group of M. priodon Bronn; for the first time appear 

 here the genera Cyrtograptus and Stomatograptus ; 

 totally absent are Rastrites, Diplograptus, and Climaco- 

 graptus. In this horizon we find already in the grap- 

 tolitic shales calcareous concretions (nodules of ellipsoidal 



