Decembeb 13, 1907] 



SCIENCE 



837 



terest. One of these, by E. Plizenmayer, deals 

 with the northern mammoth and while very 

 interesting, contains what I believe to be two 

 very serious errors. The first one of these re- 

 lates to the shape of the tusks, which are dis- 

 cussed at considerable length, the author con- 

 cluding that the tips pointed forwards and 

 downwards and were used in digging. To sup- 

 port this contention we are given figures of 

 several tusks and a copy of a drawing in a 

 cave at La Mouthe. 



It seems a sufficient reply to this last bit of 

 testimony to note that there are many other 

 figures of the mammoth in existence, including 

 various carvings, and in none of these are the 

 tusks depicted as shown in the cave of La 

 Mouthe. 



Tusks of the mammoth exist in Alaska in 

 large numbers and many have been brought 

 from there during the past few years. None 

 of them shows the great spiral twist and final 

 downward curvature of the tusks figured by 

 Dr. Pfizenmayer. Tusks of the mammoth, like 

 those of the mastodon, vary very greatly in the 

 amount of curvature and of their spiral twist. 

 As a general rule the curvature is at first 

 downwards and outwards, and then upwards 

 and inwards. The tusks figured by Dr. Pfizen- 

 mayer are very evidently those of old indivi- 

 duals and are abnormal in shape. The tusks of 

 the Beresovka mammoth do not exhibit the 

 great spiral curvature of the specimen from 

 Cracow and there is no reason to believe that, 

 as ft rule, the tusks of the mammoth pointed 

 downwards and forwards. When in excep- 

 tional cases they did, it would be quite natural 

 to use them for digging. 



The second error is in ascribing to the 

 northern mammoth a greater size than that of 

 existing elephants. Unless I am mistaken, no 

 Siberian mammoth has yet been found having 

 greater height at the shoulders than nine feet 

 six inches, a height occasionally equalled by 

 the Indian elephant and exceeded by the Afri- 

 can species, which stands eleven feet high and 

 occasionally slightly more at the shoulders. 

 Dr. Swanton, indeed, has recently recorded a 

 specimen of the Indian elephant having a 

 height of eleven feet, but this seems somewhat 

 questionable. It must not be forgotten, how- 



ever, that few elephants are allowed to reach 

 their full age and size, much less to develop 

 tusks of the greatest possible length, and this 

 partly accounts for the comparatively small 

 size of the tusks of modern elephants. 



There is no tusk of the northern mammoth 

 in existence so heavy as the heaviest examples 

 of tusks of the African elephants and there 

 are few tusks much longer than the greatest 

 recorded length found among this species. 

 The tusks of the northern mammoth average 

 • somewhat longer than those of either of the 

 existing species of elephants, but they did not 

 reach so great a diameter as the best specimens 

 of tusks of the African elephant which meas- 

 ure from nine feet to eleven feet six inches 

 long and weigh from 125 to 239 pounds for a 

 single tusk. 



It has frequently been shown that the 

 northern mammoth was no larger than existing 

 elephants, as a matter of fact it did not stand 

 so tall as the Soudan elephant, but it seems 

 difiicult to effectually dispose of the belief that 

 it was a creature of gigantic size. 



The true giants among fossil elephants are 

 Elephas meridionalis of southern Europe and 

 E. imperator of our western and southwestern 

 state-s, which stood from twelve feet six inches 

 to possibly thirteen feet six inches high. 



F. A. Lucas 



CURRENT NOTES ON LAND FORMS 



A PENEPLAIN IN THE GRAND CANYON DISTRICT 



The existence of an uplifted and dissected 

 peneplain in the Grand Canyon district of 

 Arizona has been recognized for some years, 

 and its relation to the great folds and faults 

 of the region has afforded a subject for in- 

 teresting discussions. Little has been known 

 in detail, however, regarding the peneplain 

 remnants. Dr. H. H. Robinson, of Yale Uni- 

 versity, recently offered a contribution to this 

 subject in an account of " The Tertiary pene- 

 plain of the Plateau district, and adjacent 

 country, in Arizona and New Mexico " 

 (Amer. Journ. Science, XXIV., 1907, 109- 

 129). He concludes that after the occurrence 

 of the principal displacements the greater part 

 of the region was reduced to a peneplain " of 

 practically no relief." The broad uplift of 



