578 K. ETHERIDGE ON THE PALEONTOLOGY OF THE 



mouth cannot be seen ; but the linear and isolated condition of the 

 cells and other characters are manifest. We do not see the early or 

 first cells, which should be long and slender ; but their triangular 

 form in advanced age is well shown. 



The specimens occur in fissile, hard, argillaceous limestone. 



The high latitude where these fragments were obtained (lat. 81° 40') 

 tends to confirm the belief that the Llandeilo or Caradoc series is 

 represented so far north, this being partly, if not entirely, confirmed 

 by the presence of large Maclurece and Heceptaculites, Helicocotomce 

 and Heliolites, &c. Barrande obtains Bastrites (Graptolithus) from 

 his Etage E, or base of the Upper Silurian rocks of Bohemia. 



Log. Thank-God Harbour, lat. 81° 40' N., in drift. 



Class ACTINQZOA. 



A large series of sclerodermic corals have been collected both by 

 Captain Feilden and Dr. Coppinger, and many by Mr. Hart and Dr. 

 Moss. The Bessels-Bay, Offiey-Island, and Dobbin-Bay species were 

 collected in situ. Those from Petermann Eiord, Cape Tyson, and 

 Polaris Bay are all from the drift, talus, and the ice-floe. The two 

 groups Rugosa and Tabulata are fairly balanced as regards number 

 of species, but the chief tabulate coral numerically abundant is 

 Favosites gothlandicus ; it seems to occur everywhere in the Upper 

 Silurian rocks of the arctic circle. The Tabulata include Halysites 

 (the chain-coral) in three varieties, abundant also ; Heliolites and 

 Syringopora a few specimens only ; Alveolites rare. 



Among the Rugosa, we have in the collection Favistella, Zaphren- 

 tis, Amplexus, Cyaihophyllum, Arachnophyllum, Calophyllum, JStre- 

 phodes, and Lithostrotion. 



These undoubted reef-forming corals of the Silurian epoch were 

 just as much inhabitants of warm water in southern latitudes at 

 that period as are the Sclerodermata of today in the Indo-Pacific 

 and Atlantic Oceans ; and as we know of no compound coral that 

 will exist at a lower temperature than 68° F., and as the surface- 

 waters under the equator in the Pacific have a temperature of 

 85° F., and in the Atlantic 83°, it seems clear that the range from 

 68° to 85° F. is best adapted to and not too high for the growth of 

 the reef-making species. We may fairly assume that the temperature 

 of the polar waters during Palaeozoic times was as high as that of 

 the Indo-Pacific and Atlantic now, where coral-reefs abound. We 

 are not justified in supposing that the laws regulating oceanic life 

 were very different then from those now existing (in the same groups) 

 under the equator or between the tropics. These corals were 

 forms of life which must have been tropical in habits and require- 

 ments. We know nothing of the ancient isotherms or isothermal 

 laws that then, as now, through temperature greatly governed or in- 

 fluenced the distribution of life over the globe, whether upon land 

 or in the sea. All is not due to supposed changes in the direction 

 of the earth's axis or place of the pole. We have yet to learn some- 



