Dr. WheeUon Hind — Carhoniferom Life-Zones. 63 



Gosselet (" Esquisse geol. du Nord de la France," 1880) proposes 

 to divide the Carboniferous Limestone of France and Belgium into 

 ten zones, but, judging from the lists of fossils given, probably not 

 on palEeontological grounds. He recognizes Spirifer Mosquensis as 

 occurring at horizons below that of Productus giganteus. 



It will be noted at once that the highest stage of the Carboniferous 

 Limestone of Belgium is characterized by the same zonal form 

 (P. giganteus) as that which is so typical of the lowest division in 

 Knssia, and that it is accompanied by P. cora, one of the zonal forms 

 of the highest Eussian division. 



Although, some time ago, De Koninck was of opinion that Spirifer 

 Mosquensis was found in the lowest Belgian (or Tournaisian) stage, 

 in his paper " Sur le Spirifer Mosquensis " (Bull. Mus. Roy. d'Hist. 

 Nat., tom. iii, 1883, p. 373) he showed that he had confounded this 

 species with Spirifer Tornacensis and S. ductus. In his remarks 

 on the affinities of the latter shell, he states " qu'elle en differe 

 essentiellement [from S. Mosquensis^ par sa grande taille, et, mieux 

 encore, par I'absence dans sa valve ventrale des lamelles dentales 

 divergentes, si fortement developpees dans celle de sa congenere 

 Russe." 



In a later work, De Koninck figures Spirifer spissus from Stage III 

 and S. suams from Stage II, but these, judging from the drawings 

 alone, I should not. like to say were not varieties or specimens of 

 S. Mosquensis ; certainly they have much fewer ribs than the latter 

 species. 



I have lately attempted to solve the question whether S. Mosquensis 

 really occurs in Great Britain or not. Originally Davidson figured 

 two specimens in his Monograph on the British Carboniferous 

 Brachiopoda (pi. iv, figs. 13 and 14) which agree very closely with 

 Eussian examples. Later on he was led to doubt the correctness 

 of his determination through the influence of De Koninck's work. 

 Unfortunately one of these figured specimens has disappeared, and 

 probably only that one remains which is in the collection of the 

 Eoyal Society of Dublin, but I have not been able to examine this 

 example. 



lu the Appendix to the Monograph Davidson figures two shells 

 from Scotland (pi. xxxiv, figs. 3 and 4) which closely resemble 

 S. Mosquensis in shape, under the name S. trigonalis var. hisuJcata. 

 Dr. J. Young has kindly compared these shells with a typical 

 Eussian example, and says that the Scotch examples have much 

 fewer ribs and that these are thicker. 



I have, through the kindness of Professor Lloyd Morgan, examined 

 the shell from the Oracanthus bed of the Lower Limestone shales of 

 Clifton named S. Mosquensis by Stoddart, but this reference is an 

 error, the shells having nothing in common. 



I have also examined a fine series of shells labelled S. Mosquensis, 

 from the Carboniferous Limestone of Co. Cork, in the collection of 

 the Geological Survey of Ireland, I recognize amongst them S. cinctvs 

 and S. Tornacensis of De Koninck, but not S. Mosquensis. When 

 placed side by side the difiereuces between these three species are 



