272 MR. BALL ON PLANTS COLLECTED IN MOROCCO 
but to devote himself to the interminable task of observing and 
registering the minute differences by which they are distinguished. 
they would rank the remainder as undoubted varieties of Z. 0 lis 
is one a the s closel ied to our common 
Euphrasy that shows differences more marked and more constant than 
n between it and several of the forms that we 
refer to E. officinalis leaves little doubt that it is related to the latter 
by genetic descent. This I am inclined to cite as a typical instance of 
a subspecies 
distinct species. Amongst all the modifications of E. officinalis the 
leaves vary between broadly ovate and narrowly lanceolate—having 
the broadest part in the lower half of the leaf, and thence tending to 
In £. tricuspidata the leaves are strap- 
shaped, with parallel uncut sides, and have at the summit three short 
teeth, one in the middle and one at each angle. A further mark of 
salisbur, r ‘Gensis. The first impression was that this was a case of 
hybridity, but, in the first place, the intermediate plants seemed to 
pe 8 nec ed abundantly, and, further, these forms were not 
n . 
home. If further observation should confirm that made by me 
several years ago, E. tricuspidata should be ranked as a subspecies of 
E. officinalis. 
