The marine Carboniferous of North-east Greenl. and its Brachiopod Fauna. 583 



and it should, perhaps, be specially pointed out that the characteri- 

 stic feature distinguishing Pr. cancriniformis Tschern. from the nearly 

 related Pr. Cancrini Vern., viz., the continuation of the transverse 

 wrinkles from the flanks of the shell across the median portion, is 

 clearly apparent. 



This species occurs in 4 fairly well preserved specimens of the 

 dorsal valve, in the light limestone N:o 15A from the Mallemukfjæld. 



By TscHERNYSCHEW and other writers, this species is considered 

 to be a leading form for the Arta stage \ the low est portion of the 

 Permo-Carboniferous of Russia, and is mentioned from the Auernigg 

 strata of the Carnian Alps, which, by Schellwien is reckoned as 

 the uppermost bed of the Upper Carboniferous. In the Hima- 

 layas, the species occurs in the Chitichun fauna, which Diener con- 

 siders as belonging to the lowest Permo-Carboniferous, and in the 

 Productus shales from Kumaon and Gurwhal in the Niti pass — 

 strata which Diener refers to the Permian. From Spitzbergen, 

 TscHERNYSCHEW mentions the species from the Productus-bearing 

 siliceous rocks, but Wiman has only a line about this species. 



Productus cancriniformis Tschern., in Russia, goes down into 

 the Schwagerina horizon. This species should, therefore, even though 

 its vertical extension is fairly wide, be one of the forms which here 

 indicate a higher horizon of the formations now in question, and 

 consequentl}' it points to a Schwagerina horizon as the lowest poss- 

 ible level. 



N:o 22. Productus Wallacianus Derby. 



PI. XXIX, Figs. 1—4. 

 1874, Productus Wallacianus Derby, p. 57, PI. 3, Figs. 46—48; 



PI. 6, Fig. 5. 

 1902, — Wallacei Tschernyschew, p. 270, PI. 30, Fig. 8; 



PI. 60, Figs. 19—23. 

 Two specimens of a Productus found in a light fine-grained lime- 

 stone on the Eskimo Naze (iV.o 213), a ventral and a dorsal valve, 

 I consider I should refer to the above-mentioned species, in spite 

 of the fact that the original figures are by no means very clear, even 



^ The manner in which Frech mentions tliis species in "Lcthæa palæozoica'' Vol. 

 I, 2), is somewhat peculiar, and is worth}' of mention. On page (555 he mentions 

 the species as „eine Leitform der Arta-stufe' , Avhile, on page 358 b. in a later 

 addition, he includes it among „stratigraphisch bedeutungslose Arten von langer 

 geologischer Lebensdauer". This last opinion is based on Schki.lwien (of 1902), 

 but, even if the importance of this species for the determination of levels in the 

 Permo-Carboniferous and the Permian is not very great, still, for us it is an 

 important leading fossil which indicates the Schwagerina horizon as the loлvest 

 point of comparison. 



