80 REPORT — 1875, 



condition of climate nearly approaching, if not similar to, that which is indicated 

 by the beds of plant-remains found in Greenland, Iceland, and Spitzbergen. 



Dr. Carpenter has demonstrated that the north-polar " set " or cm-rent (commonly 

 called the north-east branch of the Gulf-stream) is dependent on diminution of 

 temperature in the Polar regions, causing displacement by sinldng of the surface 

 sea-water rendered denser by cooling, and the consequent influx of lighter, that is 

 warmer, water to supply its place. Increased severity of the winter in the north 

 would therefore augment the volume and velocity of this current, and, cceteris 

 paribus, thus render milder that of Britain. This appears to be in accordance with 

 the persistent increase of cold in Greenland and Iceland simultaneously with 

 recession of the glaciers in Norway and the occurrence of milder winters in Britain, 

 and also -nath clianges which occasionally take place of a more temporary character, 

 as the occurrence of winters in America of exceptional severity, whilst the same 

 seasons were remarkable for their mildness on the eastern shores of the Atlantic, 

 and vice versa. 



Not only has the Gulf of Mexico extended far up the valley of the Mississippi, 

 but a former depression of the land has occurred m the West-Indian Islands, to 

 2000 feet and even to 6000 feet ; raised sea-beaches occm- on the west coast in 

 California ; and the Gulf of California is but an extension of the Colorado river, 

 which has been submerged. Subsidence to so gteat an extent on each side would 

 in all probability affect the isthmus in a similar manner. If such a depression took 

 place in certain areas to the extent respectively of 134 <and 300 feet only, it would 

 enable the waters of the Atlantic to flow into the Pacific Ocean. The fauna have 

 been considered to afibrd indications of a former intercommunication of the two 

 oceans by the identity or similarity of many of the Mollusca (Mr. P. P. Carpenter, 

 Brit. Assoc. Report, 1840) and also of the Echinodermata (' Depths of the Sea,' 

 p. 14) on each side. It is thus more than probable that a passage for the equatorial 

 current has been aflbrded at Panama and Nicaragua. If it occurred to a consider- 

 able extent, the north-polar cun-ent would have had no higher temperature than 

 that which it could derive from the temperate zone. Such a removal of the Gulf- 

 sti-eam is by most, if not all, considered sufficient to reduce the temperature so as 

 to cause the formation of glaciers in Britain ; but though the intense cold would 

 condense the atmospheric moisture so as to cause extensive ice-floes between 

 Greenland and Norway, there would have been but little remaining to be precipi- 

 tated in the Arctic Ocean. 



It was contended that the succession of Glacial Periods, having intervening 

 times characterized by a mild or even genial climate, as demonstrated by Mr. James 

 Geikie, might have been caused by successive depressions and upheavals of the 

 Isthmus of Central America. To obtain positive proof of this supposed change in 

 the direction of the equatorial cun-ent, it is requisite that investigations with this 

 object in view be made in Nicaragua and other parts of Central Ainerica. 



On certain Icmje Bones in Shcetic Beds at Ausf Cliff, near Bristol. 



By "William Sandeks, F.B.S. 



In the year 1844 a large cylindrical bone was found on the shore at Aust by 

 Mr. Edmund Higgins, from whom it was subsequently purchased for the Bristol 

 Museum. It measures about 15 inches in length and'about 17 inches in circum- 

 ference. About four years later Mr. Alexander Thompson, residing near Aberdeen, 

 found the largest of the bones, and generously presented it to the Museum. This 

 is about 25 inches in length, and about equal to the other in circumference, that is, 

 about 17 inches. A third bone, the smallest of the three, was found a few years 

 ago, with a large vertebra, closely adjoining the thick "bone-bed; " it is 8 inches 

 long, with a circumfei-ence of 15 inches. 



Neither of these pieces had retained its terminations ; they were therefore incom- 

 plete fragments. The two larger concurred in having a long furrow, apparently 

 adapted to receive an artery or vein ; and the late Mr. Samuel Stutchbmy, who 

 was then Curator of the ]Museum, observed that an analogous furiow pnsfed along 

 the femur of the frog, and suggesttd that these bones might have belonged to 



