72 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



ditions he coined the words "homogeny " and "ho- 

 moplassy. " The terms introduced by Lankester differ 

 from mine in that they convey implications as to the 

 origin of the respective conditions. 



3 4 



Fig. 23. Feet of (1-2) Uma scoparia Cope, from near Tucson, Arizona, 

 and (2-3) Ptenopus garrulus Smith, from South Africa. No. i, manus ; No. 2, 

 pes ; Nos. 3-4, pes. Nos. 1-2, original; Nos. 3-4, from Boulenger. 



An illustration of homoplassy is to be seen in the 

 spines on the head, tail, and feet of lizards which in- 

 habit desert regions. The parallelism between Phry- 

 nosoma of the American dry regions, and the Moloch 

 of the corresponding climates of Australia has been 



