The marine Carboniferous of North-east Greenl. and its Brachiopod Fauna. 581 



by Waagen to be specially variable, and the specimens figured pre- 

 sent little resemblance to each other but, in the description it is 

 stated that sometimes the curve "remains rather flat in the apical 

 region and then suddenly bends down to the front". 



Our specimen exhibits evident differences from other forms be- 

 longing to the striatus group. Pr. anomalus Keys, (figured in 

 TscHERNYscHEW, 1902, PI. LXIIl, Fig. 10) and Pr. mytiloides Waagen 

 have a more regular sculpture, with the longitudinal striæ straighter 

 and more continuous, while the ventral valve is considerably flatter. 

 Pr. mongolicus Diener (1897 : Part III, PI. 4, Figs. 8—10 and 1899, PI. 6, 

 Figs. 7 — 8) agrees, perhaps, somewhat more closely with our specimen 

 as far as size is concerned (an entire specimen is aboutSO mm., in length) 

 and in the general form and the arching of the shell, but it differs 

 from it by the umbo projecting somewhat beyond the hinge-line, 

 and also by its different sculpture which, in the case of Pr. mongo- 

 licus Dien., consists of fairly distinct and regular radial striæ and 

 close, sharp transverse wrinkles. 



Prod, striatus Fischer, as figured by Davidson, has a sharper 

 and more regular radial sculpture, while the shell is flatter. 



N:o 20. Productus simensis Tschern. 



TSCHERNYSCHEW, 1902, pp. 626--628, PI. 35, Fig. 5; PI. 55, Figs. 

 2—5. 



A compressed specimen of the ventral valve of a finely striated 

 Productus, found in the black shaly rock {N:o 190) in the Conglo- 

 merate section, at about 200 metres above sea-level, together with 

 Spirifer supramosquensis Nik. and Sp. rectangulus Кит. var. alta, ought 

 probably be referred to this species. 



The specimen is too badly preserved to be figured, but from its 

 character it may easily be discerned that it is most closely con- 

 nected with the species mentioned above. Its elongated form speaks 

 most decidedly against its being referred to Prod. Cora d'ORB. and 

 the nearest related forms, and brings it into closest connection with 

 Prod, tenuistriatus Vern., and Prod, simensis Tschern. 



The absence of wrinkles on the flanks, and the abrupt involu- 

 tion of the valve near the beak speaks most for Prod, simensis, but 

 the compression that the valve has undergone, makes it impossible 

 to decide if its transverse profile in the anterior part possesses the 

 elevation in the middle and the sharp slope towards the flanks, 

 which are characteristic for Prod, simensis. 



In this connection reference should be made to the doubts ex- 

 pressed by Gröber (1908 and 1909) respecting the value, from a 

 stratigraphical point of view, that can be ascribed to Productus Cora 



