EQUIPMENT, ARMS, AND SPECIMENS 747 



desirable are the skulls of specimens with really large tusks 

 which would show the changes of bone structure which ac- 

 company gigantic tusk development. The largest skulls at 

 present preserved in museums possess tusks of considerably 

 less than two hundred pounds per pair, which are less than 

 half the weight of record tusks. It is well to bear in mind 

 that our large mammals are disappearing more rapidly than 

 the smaller ones, and in the districts where they are now 

 rare special efforts should be made to obtain and preserve 

 specimens before their extinction. In order to determine 

 the characters of the geographical races of a species it is 

 necessary to have specimens for study from every district 

 inhabited by the species. Game reserves can only protect 

 or preserve species in certain limited areas, and we cannot 

 therefore possibly preserve by such means all the geograph- 

 ical races of widely distributed species. To carry out such 

 complete preservation would require the protection of all 

 the species of game animals throughout their entire ranges, 

 which is obviously impossible. It should be our especial 

 purpose to obtain specimens of the species which are disap- 

 pearing most rapidly, in those districts where they are 

 already rarest. 



The salt method of preservation here described is essen- 

 tially that of Carl E. Akeley, and was the one employed by 

 the Smithsonian African expedition under the direction of 

 Colonel Roosevelt. Owing to the great quantities of salt re- 

 quired both in dry-salting the skins in the field ^and later in 

 packing them in barrels for shipment, it is a very expensive 

 process. To the cost of the salt must be added the much 

 greater cost of transportation of the skins in the field 

 due to the added weight of salt. It has great advan- 



