28 



KNOWLEDGE & SCIENTIFIC NEWS. 



I Mar., 1904. 



respect the camels have indeed beaten the horse, haMn.^ 

 entirely got rid of the splint-bones representing the outer- 

 most pair of the original four toes. Further, in having 

 exchanged the hoofed for the cushioned type of foot, they 

 have undergone a kind of retrograde de\elopment. for 

 which there is no parallel in the horse line. 



Fig' S. — Skull of Modern Camel, showing the reduced number of upper 

 incisor teeth, and the ring of bone round the eye-socket. 



Here a brief diversion must be made to notice an 

 extraordinary North American Miocene form, which is off 

 the mam line. This is the giraffe-necked camel (Alti- 

 camdas), a creature of the size of a giraffe, with similarly 

 elongated neck and limbs, and evidently adapted for 

 browsing on trees. The feet and number of teeth were 

 generally similar to those of Procamelas. Unlike the 

 giraffe, the length of the limbs is due to the elongation 

 of the bones of the upper segments (femur and tibia) and 

 not the cannon-bones : while the fore-limbs are not 

 higher than the hind ones. The length of neck is due 

 to the elongation of the anterior neck-vertebra-; if the 

 hinder ones had been lengthened, the hei.ght of the body 

 would have been increased without any compensating 

 advantage. This creature affords one of the most extra- 

 ordinarv instances of special adaptation known to science. 



The remaining space at my disposal must be devoted 

 to certain considerations concerning the birth- 

 place and geographical distribution of the group. 

 It is claimed by Transatlantic pahfontologists 

 that North America was the original home of 

 the Camelidii, and so far as the earlier members 

 of the group are concerned, there is nothing at 

 present to justify a contradiction of this. The 

 case is, however, \-ery different with the latter 

 forms. We have seen that in North America 

 the formation of a complete cannon-bone did 

 not take place till tlie Pleistocene, at which 

 epoch true camels also made their first appear- 

 ance. But such camels, with complete cannon- 

 bones, were in existence in India in the early 

 pliocene. Ob\ iously, therefore, the evolution ot 

 these animals must have taken place somewhere 

 in Asia; this \iew being supported by the oc- 

 currence there of the aforesaid Pnraeamelas. 

 1 lence it is quite probable that some of the 

 earlier stages of the evolution of the group may 

 have been carried out in ;\sia, when that conti- 

 nent was united by way of Pehring Strait with 

 North America. The Siwalik camel, it may be 

 added, may ha\'e gi\en rise totlie existing two- 

 humped Bactrian species ; while from the ex- 



tint t Russian and Roumanian camels the single humped 

 Arabian species may have sprung. 



W'ith regard to the llamas of South America, palaeonto- 

 logy goes to prove that the ancestral forms first 

 obtained entry into that contintent from the north dur- 

 ing the Pliocene period, when free communication 

 was established between North and South America. 

 Now all these ancestral forms, of which there are several 

 distinct generic types, appear to have complete cannon- 

 bones. Consequently, unless we are prepared to admit 

 that these compound bones have been independently 

 evolved in the camels and the llamas, the latter cannot 

 have been derived from the known North American 

 Pliocene forms, in which the union of the constituent 

 elements of these compound bones was incomplete. 

 Consequently, it seems a probable supposition — and this 

 is supported by the above-mentioned structural resem- 

 blance between the cheek-teeth of the Siwalik camel and 

 those of the llamas — that the latter animals, like the true 

 camels, were evolved in Eastern Central Asia, whence 

 they reached South America by way of the Pacific 

 border of the northern half of the New World, possibly 

 over land long since submerged. 



The PKotogroLphy of 

 Electric Spa^rks. 



The Photography of Some Electrical Phenomena 

 was the subject of a lecture delivered on January 25, 

 1904, at the Camera Club, Charing Cross Road, by Dr. 

 George H. Rodman. 



The lecturer commenced by describing t!ie method 

 that he had adopted in obtaining the photographic repre- 

 sentation of electric sparks from a lo-inch induction coil 

 actuated by accumulators. It seemed to matter but little 

 what voltage was used in the primary circuit, and the 

 results shown were produced at a voltage varying from 

 fi to 24 in the primar)'. 



Single Fo.siiive Di.scharge. 



