394 Dr. 0. A. L. Morch—On the Crag of Iceland. 



than the Crag. The Crag is not found in G-reenland, but a formation 

 probably corresponding to the layers of Fossvogur and Arnabauli. 

 In the following paper I have given a list of thirteen species of shells 

 from Pattorfik, in the Omenaksfjorden. They are still living in the 

 seas of Greenland, except Gyrtodaria siliqua, Spgl., a Newfoundland 

 species, and Panomya Norvegica, Spgl. (the form P. arctica, Lam.), 

 found on the north coast of Iceland and in the Cattegat. 



6. H. BinJc. Om den geographiske Beskaffenhed af de danske 

 Handelsdistrikter i Nordgronland tilligemed en Udsigt over Nord- 

 gronlands Geognosie, 1852. (Kgl. danske Videnskabernes Selskabs 

 Skrifter, 5 E^kke, 3 Bind.) 



The Crag-formation of Hallbjarnastadir is characterized by the fol- 

 lowing fossils : — 1. Species not found living but fossil in England 

 and Belgium : — Corbidomya, two or three species ; Actceon Noce, Sowb. ; 

 Natica varians, Duj. ; N. Jiemiclausa, Sowb. ; N. occlusa, Wood ; 

 Littorina littorea, the Crag variety, Buccinopsis crassum, Nyst, ; Nassa 

 monensis, Forb. ? ; Valuta, sp. ; Trochus, two sp. ; Cyrtodaria Heerii, 

 Winkl. ; Mactra, two or three sp. ; Tellina obliqua, Sowb. ; Tellina 

 prcBtenuis, Leathes ; Cyprina Gaimardi, Eobert ; G. rustica, Sowb. ; 

 G. Islandica, L., var. pumilio ; Mytilus Jiesperianus, Lam. 



2. The following species are found living in the arctic regions, and 

 are found fossil in the Crag of England : Natica Grcenlandica, Beck ; 

 N. clausa, Sowb. ; Tritonium Groenlandicum, Chem. ; Tr. undatum, var. 

 pumilio; Fusus propinquus, Aid. ; Fusus fornicatus, Fabr. ; Pleurotoma 

 turricula, Mtg. (but very large) ; PL rufa, Mtg. ; PI. Treveylliana, 

 Turt. ; Admete viridula, Fabr. ; Patella pellucida, L. ; Teredo, sp. ; 

 Solen siliqua, L. ; S. ensis, L. ; Saxicava Norvegica, Spgl. ; Gyrtodaria 

 siliqua, Spgl. ; Mya truncata, L. ; M. arenaria, L. ; Tellina calcarea, 

 Chem. ; Gyprina Islandica, L. ; Astarte crebricosta, Forb. ; A. com- 

 pressa, L. ; Gardium Groenlandicum, Chem. ; Modiolaria nigra, Gray ; 

 Mytilus edulis, L. ; Cardium ecJiinatum, L. 



The following species only are found living : Acrybia lutea, Gould ; 

 Littorina Grcenlandica, Chem. ; Tritonium Tottenii ; Tritonium scalari- 

 forme. Beck. 



At present the north coast of Iceland is quite arctic, but in the 

 Crag-period the temperature must have been much milder, at least 

 as at present on the west coast by Eeikiavik. The following genera, 

 which indicate a southern climate, are still found on the west coast of 

 Iceland : ActcBon, Trochus, Patina, Nassa, Mactra (elliptica), none of 

 which are arctic ; Littorina littorea, Solen ensis, S. siliqua, Cardium 

 echinatum, none of which are arctic shells, have not been yet discovered 

 in Iceland, but may j)ossibly be found there hereafter. The change of 

 the climate of the north coast of Iceland to one of a true arctic nature 

 probably has resulted from an elevation of the land in that part 

 which prevented the free passage northwards of the great equatorial 

 current. 



Natica aperta is considered by Prof. C. Mayer to be a tropical 

 form, but this species is, on the contrary, a true Glacial form. Prof. 

 Winkler believes that the dwarf variety of Cyprina Islandica 



