The Speeton Beds and their Equivalents. 425 



base of the " Petchorian " stage^ The Eouillier stage is very rich in 

 fossils and its fauna has been carefully worked up. It is divided 

 into two zones, the upper of which contains Olcostephanus {Craspe- 

 dites) nodiger, C. haschpuricus, and Oxynoticeras subclypeiforme, and 

 the lower contains Olcostephanus ( Craspedites) subditus, C. fragilis, 

 and Oxynoticeras catenulatum. Belemnites lateralis, B. russiensis and 

 £. mosquensis are found in both zones ; Belemnites subquadratus is 

 also met with, though rarely. 



Turning again to Speeton we find that the beds there (D. 4 to D. 8) 

 corresponding with the upper stage of Eouillier are those situated 

 immediately below D. 1 to D. 3, and that they contain the following 

 Cephalopods, viz., Belemnites lateralis, B. russiensis, B. subquadratus, 

 B. explanatoides, Olcostephanus (Craspedites) fragilis, C. subditus, 

 and Oxynoticeras, cf. catenulatum. Excluding the two last-named 

 Ammonites, which were found to be too young for decisive identifi- 

 cation, the list may be completed by the Cephalopods of Lincolnshiie 

 of corresponding horizon (Spilsby Sandstone). This supplies an 

 undoubted Craspedites subditus, so that there remains only Oxyno- 

 ticeras catenulatum upon which any doubt might be thrown. But 

 even if the last-named species did not exist at Speeton, the number 

 of forms common to the Russian and English horizons in question 

 would be sufiicient to prove the relationship between them. 



We now reach the beds forming the base of the Craspedites 

 subditus and C. fragilis beds, which in Russia are rich in Ammonites 

 of the Virgati group. Two zones have been observed up to the 

 present time, viz., the zone of Virgatites virgatus, and V. Pallasi, and 

 that of V. triplicatus and V. Blakei. Representing these zones at 

 Speeton there are (1) the " Coprolite bed," (2) the bituminous 

 schists containing crushed Ammonites, and Belemnites magnificus, B. 

 porrectus, and B. obeliscoides, which are observed at Speeton, below 

 the Belemnites lateralis beds. The Ammonites found in the "Copro- 

 lite bed " are too fragmentary to be identified with exactness ; but 

 the following species were approximately determined, viz., Virgatites, 

 cf. V. Panderi, Virgatites, cf. V. Tchernyschovi, Virgatites, cf. V. 

 scythicus, Virgatitus, cf. V. dorsoplanus, Virgatites, cf. V. miatsch- 

 Icoviensis, Perisphinctes lacertosus. Going down still lower in the 

 stratigraphical series undoubted Kimmeridgian beds are met with 

 containing Roplites eudoxus, H. pseudomutabilis, and H. subundarce. 

 The beds are the same as those which constitute the base of the 

 Virgati beds in Russia. Thus, even putting aside palgeontological 

 evidence, the stratigraphy alone would suffice to prove that the 

 " Coprolite bed " E, and the bituminous schists forming its base 

 correspond to the Virgati beds of the Russian Jurassic. The 

 palaeontological evidence, however, is not so convincing, owing to 

 the bad state of preservation of the Speeton fossils, and an imperfect 

 knowledge of the lowest zone of the Virgati beds. Notwithstanding 



' This sub-division has been so designated by M. Pavlow. It is a well developed 

 horizon, characterized by a special fauna. It was first discovered by Keyserling, 

 who described it in his " "Wissenschaftliche Beobachtungen auf einer Reise in das 

 Petschora Land, 1846." 



