96 | PITTONIA. 
Nothing which authors have thought to add, from Western 
America, to Potentilla, will introduce any new elements of 
diversity into the genus in so far as habit is concerned ; for 
of the Horkelia series the first two species are at perfect 
agreement, in this respect, with the commonest typical 
Potentilla of the region which they inhabit, namely, P. 
glandulosa ; and the bulk of them fall as readily in with P. 
gracilis and its near allies, in so far as mode of growth and 
characteristics of inflorescence are concerned. The only thing 
which gives to many of them a different look is the more dis- 
sected figure of the leaflets; but this mark, confessedly of no 
generical value even if it were universal, entirely fails in at . 
least a half dozen otherwise most typical Horkelias, whose 
foliage is just that of the pinnate-leaved types of the more 
historical Potentilla. In most representatives of the Ivesia 
phase we are presented with short crowded and apparently 
verticillate leaflets ; and this peculiarity, even if it were other- 
wise unknown in the alliance, would of itself have no more’ 
signifieaney than it has where, upon the Ivesia territory, it 
recurs in certain species of Polemonium and Oxytropis. But 
within the Old World type of Potentilla there is one species, 
P. verticillaris of China and Siberia, marked by essentially 
the same kind of foliage. The few Ivesias which bear their 
flowers in a close terminal cluster on erect and firm leafless 
and scape-like stems are the only-plants, among all here under 
consideration, which will carry into Potentilla, as of old ac- 
cepted, something slightly different, in the way of habit, from 
what has long had place there. 
The floral characters of Horkelia have been said to be, a 
` eampanulate calyx, few and definite stamens, the latter with 
subulate or petaloid-dilated filaments. The calyx is, indeed, 
campanulate in the original of the species and several more, 
while in others it is as nearly rotate as in typical Potentilla. 
But what if in Horkelia it were always campanulate ? Would 
it even then stand at all in the way of combining the species 
with the old Potentilla ? There can only be a negative answer 
to these questions, if we look about amongst other assem- 
