330 MONOGRAPH OF THE BRITISH SPECIES OF EUPHRASIA. 



The species may be divided into three series. Series I. comprises 

 E. pectinata, E. Maximowiczii, E. Tataiica, E. stricta, E. piimila, 

 E. borealis, -whicli, among other distinctive characters, have com- 

 paratively larger flowers. Series II. comprises species having 

 comparatively smaller flowers ; they are, E. ccerulea, E. nemorosa, 

 E. vnUtifolia, E. Americana, E. carta, E. occidentalh, E. Canadensis ? , 

 E. latifolia, E. Foulaensis, E. mollis, E. Oakesii, E. gracilis, E. Li- 

 hiirnica, E. Cehennensis, E. minima, E. Tatrce, E. Willkommii, 

 E. Scotica. Series III. comprises species which have a morpho- 

 logically more isolated position ; they are, E. hirtella, E. grandi- 

 flora, E. Jaeschkei, E. Regelii, E. drosocalyx, E. pulchella, E. 

 micrantha, E. hrevipila, E. tenuis. 



We will first take into consideration Series I. In the Plan 

 we see how isolated are the areas of E. pectinata, E. stricta, E. 

 Tatarica, and E. borealis, all nearly related. We see the area 

 occupied by E. Maximowiczii distinct from that of E. Tatarica, but 

 the one touching the other. E. pumila and E. stricta are similar 

 examples. The formation of all these species Prof. Wettstein con- 

 siders to have been due to climate, and not to hybridity. The 

 wide distribution of Parvijiora, from -Japan to Spain, points to a 

 time very far back, viz. to the tertiary epoch, when a group of 

 species of which the present are representatives, altered or un- 

 altered, occupied an extended area, but reduced in dimension in 

 Europe by the post-tertiary ice age. E. Tatarica occupies a similar 

 area ; it extends in Asia to 70°, but has a reduced area in Europe. 

 If we suppose E. Tatarica to have been the parent species, much 

 light will be thrown on the connection and distribution of the whole 

 group. In tertiary times it extended from East Asia to Europe. 

 During the glacial epoch its northern range was diminished, but 

 later on, viz. after the last glacial period, it advanced again north- 

 wards. During this latter epoch climatic influences split the species 

 into three — E. pectinata in the Mediterranean region, E. stricta in 

 the Baltic, and E. Tatarica in Central and East Asia from the 

 Black Sea to the Inkolan Mountains, occurring also in France, 

 Italy, and Switzerland ; while in the Pacific, in the Japanese 

 Islands and opposite coast a new and allied species, E. Maxi- 

 moiciczii, was evolved. The special climate of England and 

 Scotland and adjoining islands brought E. borealis into existence. 

 The isolated position of E. Tatarica m Italy, France, and Switzer- 

 land betokens a former wider range. The present southern range 

 of E. pectiyiata and its absence on the north coast of the Adriatic 

 point to a northern ancestor driven southwards by severity of 

 climate. Thus, at the end of the tertiary epoch some of the 

 members of the group we have been considering had been formed, 

 and some have since been formed and fitted to the areas which 

 they inhabit, and their rank as species is equal ; these species 

 are, E. pectinata, E. Tatarica, E. Maxiiiwwiczii, E. stricta, E. 

 pumila (this last derived from E. stricta at a later date), E. 

 borealis. The ancestor of these Prof. Wettstein proposes to name 

 E. palcEO-pectinata. 



