The marine Carboniferous of North-cast Greenl. and its Brachiopod Fauna. 579 



The other specimen is smaller and not so well preserved, but 

 this one, too, shows the characteristic of a high visceral room. 



Specimens from Russia, Spitzbergen and North-east Greenland 

 have, in general, the same dimensions, while those from North 

 America, figured by Stuart Weller, are considerably smaller. 



The species is abundant in Spitzbergen and Beeren Eiland in 

 the Spirifer limestone, and in Russia it goes from the Omphalotro- 

 chus horizon up into the Arta stage. In North America it occurs 

 in the Mississipian (Chester Group). 



Productus sp. indet. 2 (of the semireticulatus group). 



Of forms belonging to the semireticulatus group, there have been 

 found fragmentary specimens, all ventral valves: — 2 specimens in 

 the grey, fine-grained limestone {N:o 20A) found as free-lying frag- 

 ments at the Eskimo Naze, and 2 specimens, each found in a 

 boulder of the white "conglomerate"-like limestone from Eskimo 

 Naze {N:o 20A) and from the mainland behind Henrik Kröyer's Islets 

 {N:o 179). There is some difference between these two types, each 

 of which probably represents a species. 



The first have the concentric ornamentation well developed and 

 regular, so that the reticulate sculpture appears rather plainly. The 

 specimens are fairly young, and show just a beginning of the geni- 

 culation of the ventral valve for the л'isceral room. The length is 

 almost 30 mm. 



The latter have the concentrical sculpture less sharp, appearing 

 more in the form of wrinkles, so that the reticulate sculpture be- 

 comes fairly irregular. The specimens are somewhat compressed; 

 this species has been of smaller dimensions than the former, as the 

 ventral valve, with a length of about 20 mm., proves an evident 

 geniculation. 



N:o 18. Productus longispinus Sow. 



For synonyms see Fliegel, 1901, p. 100. 



Of this species, a ventral valve has been found 90 metres above 

 sea-level on Amdrup's Land at the Eastern river, in a dark, some- 

 what crystalline limestone {N:o 125). 



The specimen has a length of 13 mm., and a height of 17 mm. 

 and belongs to that form of the species without sinus, and con- 

 sequently has had the shell equally vaulted. 



The agreement is very great between our specimen and those 

 which ScHKLLWiEx (1900, p. 56, PI. VII, Figs. 4 — 7) mentions and 

 figures from Teufelschlucht in Trogkofel and Nikitin (1890, p. 159, 

 PI. I, Figs. 7 — 12), from the Gshel stage of the Russian Carboniferous. 



