I 



50 



GEOGKAPHICAL DISTRIBUTION 



meridians while the elevated land that Mr. Wallace has suggested as existing id later 



Tertiary 'times where the northern part of the Bay of Bengal now is, 1 enabled an 



foi 



typ 



tension of the Himalo-Chinese meridian to take place towards the end of the last 

 period of stability, or perhaps even at the beginning of the last period of retreat, into 

 Southern India. The fact that the South Indian species are so few curiously confirms 

 the idea that it was not in existence during earlier times. And equally striking are the 

 facts that one of the species (P. zeylanica) is a member of a highly natural group of 



the rest of which have their seat in the Indo-Chinese division, while the other 

 {P Perrotietii) has its nearest allies in two Kansu and Szetschuan species (P. macrosiphon, 



scicola); for Mr. Wallace's suggestion is made in order to explain how "a few Malayan 



mav have migrated to the Peninsula of India and have been preserved only in 

 Cevlon and the Nilgheries," and these two species of Pedicularis show how equally 

 applicable it is in explaining the presence of a few members of an Arctic- Alpine genus. 



That zonal distribution was at some time possible between the southern ends of the 

 European and Siberio* Caucasus meridians is perhaps evidenced by the existence in Asia 

 Minor of P. comosa. But the evidence is inconclusive since P. comosa extends far along 

 the Siberian meridian, and may have thus a polar derivation. Equally inconclusive is 

 the evidence afforded by the existence of forms so closely allied as P. acaulis and 

 P. RegeUam or as P. asplenifolia and P. alhiflora in the European Alps and in the Himalayas 

 respectively. For, as regards the former two, we find an intermediate form in North 

 China that is, on the Himalayan meridian, but nearer the Circumpolar province ; as regards 

 the latter two, we find an allied form (P. pedicellata) within the Circumpolar province 

 now. The latter fact equally invalidates the evidence from P. rostrata (European) and 

 P. Nor 'dma nniana (Caucasus). 2 It should be noted in passing that the two South Indian 

 species just dealt with are both examples of species with corollas somewhat highly 

 specialised in most respects (that of P. zeylanica being of Rhyncholophous, that of 

 P. Perrottettii even of Siphonanthcus type), and yet that both are beakless. They thus 

 appear to afford strong confirmation of the general evidence from morphology that the 

 appearance of a beak to the corolla was a phenomenon of comparatively recent occur- 

 rence — that beakless corollas are the more archaic. 



That zonal distribution once took place between the southern ends of the American 

 and the Himalo-Chinese meridians appears possible from the fact that the members of 

 the most highly specialised American groups (P. incurva, attollens* groenlandica) have their 

 iearest known ally in a Himalayan species (P. excelsa). Confirmatory of this too is the 

 extraordinary affinity between the Himalayan P. lachnoglossa and the American P. ParryL 

 But it also appears as if the ocean barrier which now prevents such communication had 

 been formed prior to the appearance of opposite leaves as a character in this genus. 

 Another fact that strongly corroborates the idea that the genus was not only originally 

 an alternate-leaved one, but that the character of opposite leaves is late of evolution, is 



— ^—— ■!■ » ■■ I I ■— ■ ' ■ *■«■—■—"« ^1^— — ■!■■ ■ !■■■ .... ' ' 



1 Froeeedingi of the Moyal Geographical $ 

 prevailed in northern India to the east of Agra. 



1 



3 



But there is no evidence that marine conditions have ever 



•known 



M 



turn 



on an hypothesis of H Migrati 

 of comparative "Permanence 



>> 



Mediterranean 



that 



These 



tropical or sub-tropical genera. Mr. C. de Candolle has shown this as regards Meliacea 



%j — — •— — • — * ■— -w ^ - " ^ - ■ ■— -w — — — - — — — v — - - ■ — * — — — — ~-j — — — — * — — — — — - — ■— — */ »»■■* 



Teg&rds genera like Abelia, common to Mexico and to Indo-China ; and a recent indication of the same thing is the discovery 



i n««^««*i o^ii«4* ^c „- *\ _.»_ i_«*.«. -_ ..___. ^___-_ 



mic in tha Sandwich Islands, in Burma. 









