The marine Carboniferous of Nortli-east Greenl. and its Brachiopod Fauna. 571 



of the hinge-line 40 mm., thickness of the ventral valve about 

 19 mm. 



By the internal structure of the valve and its well developed 

 dental plates, this species must, most undoubtedly, be referred to 

 that group of Spirifers characterized by Sp. mosquensis, but it is 

 distinctly differentiated from all the other species belonging to the 

 group by its fine sculpture. The species to which Sp. fulmari bears 

 the greatest resemblance is Sp. Fritschi which possesses the same 

 general form but, in addition to its characteristic sculpture, Sp. ful- 

 mari, differs from Sp. Fritschi by its greatly convex shell, its power- 

 ful and greatly projecting beak and its weak sinus. 



N:o 10. Spirlfer rectangulus Kut. var. alla, nov. var.? 



PI. XXVIII, Fig. 1—6. 



The three specimens — differing somewhat from each other — 

 of a species belonging to the Sp. trigonalis group that form the pre- 

 sent material, it has been impossible to identify with certainty as 

 belonging to any species previously described; neither, from the ma- 

 terial at hand, have I been able to establish a new species, especially 

 as the species which belong to this group present rather great limits 

 of variation. 



The designation chosen above for the form now in question, 

 indicates that I am most inclined to refer it as a variety to Sp. rect- 

 angulus Кит., although, in certain respects, it considerably exceeds 

 the limits for variation which we, in accordance with Tscherny- 

 scHEw's wealth of illustrations (1902, PI. VIII, Fig. 1; PI. XLI, Figs. 

 1 — 5, pp. 545 — 548) should consider as appertaining to this species. 

 Frech's (1900, PI. 47 c. Fig. 7) figuring of Sp. rectangulus Кит., from 

 Almasnaja, at Donetz, points rather to a variation in the same direc- 

 tion as these specimens from North-east Greenland. In Stuckenberg, 

 too (1905, PI. 3, Figs. 3 — 7) there are figured specimens of Sp. rect- 

 angulus Кит. which have the variation of a higher shell and a 

 greatly rounded anterior margin. 



For the sake of comparison, therefore, all three specimens have 

 been figured here: Specimen I, Figs. 1 — 4, shows a wider form; 

 specimen II, Fig. 5, presents a considerably longer form, but, as 

 shown by the course of the striae of growth, it proves to stand in 

 connection with the broader form, so that the shell's greater length 

 has increased wåth age. Specimen III, Fig. 6, agrees in form pretty 

 well with the preceding, but the shell is so weathered that the 

 sculpture is indistinct, nothing being visible of the slriæ of growth, 

 especially. 



