NORTON! MIGRATIONS OF SMILAX 283 



Smilax hispida has no European relatives but can, however, be 

 traced back to India in another direction. S. californica Gray, 

 a closely allied form, is found in a small area in northern Cali- 

 fornia and southern Oregon, where it was apparently stranded 

 when its connection with the rest of the world was destroyed by 

 some disturbance in the past. The next species in point of rela- 

 tionship is S. Sieboldi Miq. of Japan and Korea. South of Korea 

 we find no near relatives until we reach Yunnan, where S. sco- 

 binicaulis Wright fills in a space in the trail, both geographically 

 and phylogenetically. S. scobinicaulis links up closely with the 

 imaginary primitive types that can be constructed from the 

 maze of inter-related species in the home area of the genus. In 

 this migration we have a fine case of simple orthogenetic pro- 

 gression, with each successive step set off from the last by a bar- 

 rier and with its nearest relatives in their proper places in the 

 sequence. 



Smilax herbacea L. and its relatives have followed the same 

 path taken by S. hispida but have spread further, both in area 

 and in differentiation of characters. While the other American 

 groups have not left so plainly the tracks of their migrations from 

 their Asiatic home, there can be little doubt that careful research 

 will connect them all with the original stem. 



The eastern and western migrations of Smilax have met and 

 overlapped in the eastern United States, but it is probable that 

 both waves are still moving. S. hispida has not as yet reached 

 the Atlantic ocean, while S. rotundifolia is plainly stretching west 

 through Texas to the Pacific. Eventually it is to be supposed 

 that the waves will meet again in China. When this has oc- 

 curred in any group the geologic record is necessary in tracing 

 the course of the migration. In this connection it is interesting 

 to note that the type of the fosssil S. lamarensis Knowlton, from 

 the Yellowstone, has been examined and found to show an un- 

 doubted intermediacy between S. californica and S. hispida. 

 To complete the geographic trail it is only necessary to find a 

 fossil form from the North Pacific coast. In the accompanying 

 chart (fig. 1), based on M creator's projection of the globe, the 

 longitudinal separation of the successive steps in the northern 

 zones is greatly exaggerated. 



