612 



8GIENGE. 



LN. S. Vol. V. No. 120. 



position of the condyle high above the 

 tooth line. (3) The incisors are reduced to 

 a single pair in the lower jaw of Calamodon, 

 and are probably completely absent in 

 Stylinodon. (4) The posterior portion of 

 the tooth line below passes well behind the 

 anterior border of the coronoid. (5) The 

 canines in all are enlarged, and in Calavio- 

 don and Stylinodon grew from persistent 

 pulps, as in Megalonyx. (6) All the mo- 

 lars and premolars in Stylinodon are greatly 

 elongated, of persistent growth, and the 

 enamel is confined to narrow vertical bands. 

 (7) There is a thick deposit of cementum 

 on the dentine in those situations in which 

 the enamel disappears. (8) The cervical 

 vertebrae strongly resemble those of the 

 Gravigrada. (9) There were well devel- 

 oped clavicles present. (10) The humerus 

 bears a striking resemblance in all of its 

 essential features to those of Mylodon, Mega- 

 lonyx 2iJi6. Megatherium. (11) The ulna and 

 radius are also similar. (12) The manus 

 is almost identical with that of the ground 

 sloths. (13) The humerus and ulna and 

 radius have no medullary cavities ; and 

 (14) the femur has all the characteristic 

 features of the Gravigrada. (15) The 

 lumbar vertebral formula was the same as 

 in the Edentata. (16) The pelvis is de- 

 cidedly Edentate and (17) the caudals 

 bear a striking resemblance to those of the 

 Ground Sloths." 



It follows, or at least is extremely prob- 

 able, that not only the Gravigrada, but all 

 the South American Edentates had their 

 origin in North America. Thus a group 

 which has been traditionally assigned to 

 South America now appears to have taken 

 its origin in the north, for the sloths first 

 appear in the Santa Cruz beds of Patagonia, 

 which are not older than the North Ameri- 

 can White River beds or Oligocene, whereas 

 in North America they are found immedi- 

 ately over the Cretaceous. The importance 

 of this discovery can hardly be exaggerated. 



both because of its bearing upon phylogeny, 

 and upon geographical distribution. It ap- 

 pears certain that there was an early land 

 connection between North and South Amer- 

 ica, and it is in the highest degree improb- 

 able that the sloths found their way to 

 South America by way of Asia and Ant- 

 arctica, as Lydekker has suggested. This 

 early land connection enables us to connect 

 the South American Ungulates, especially 

 the Litopterna, with the American Condy- 

 larthra, as Cope and others have suggested, 

 so that it will throw renewed life into the 

 study of the genetic relations of these 

 northern and southern faunas. Another 

 important result is, that the Edentates are 

 proved to be of tritubercular origin, thus 

 reinforcing the evidence of a trituberculate 

 stem form of all the mammalia. 



H. F. O. 



CURRENT NOTES ON METEO_ROLOGr. 

 THE EXPLORATION OF THE AIE. 



In Appalachia, Vol. VIII., No. 1, pp. 179- 

 189, Mr. A. L. Rotch has a paper on ' The 

 Exploration of the Free Air,' in which he 

 gives a general outline of the way in which 

 this work is being done, by means of moun- 

 tain stations, balloons, cloud measurements 

 and kites. The following facts are of general 

 interest: The first summit station in the 

 world was established on Mt. Washington, 

 N. H. (6,280 ft.), in 1870. The Pikes Peak 

 station (14,134 ft.), now closed, was for 

 many years the highest in the world, but 

 at present the highest station is that of the 

 Harvard College Observatory on the summit 

 of the volcano El Misti, in Peru (19,200 ft.). 

 On Mont Blanc there is a station at the 

 Eochers des Bosses. (14,320 ft.), operated 

 during the summer, and on the summit 

 (15,780 ft.), the latter still being idle. The 

 Sonnblick (10,170 ft) in the Austrian Alps; 

 the Saentis (8,200 ft) in Switzerland; Monte 

 Cimone (7,100 ft.) in the Apennines, near 

 Lucca, and Ben Nevis (4,400 ft.) in Scot- 



