OF THE GENUS ARENARIA. 829 
geographical distribution and systematic variation as shown in 
the large or small number of species circumscribed by the more 
important generic types, I propose to define the limits and scope 
of the genus more in accordance with the views expressed by 
Fenzl, rather than with those of botanists with a more syn- 
thetie bias. 
No systematic account of the known species of Arenaria has 
hitherto been given. A conspectus of sections, preceded by a 
short historical introduction, was published in November 1895 
as a preliminary instalment* of a detailed examination of the 
species. The undiseriminating list of the species by Persoon f, 
and the fragmentary and meagre descriptions of those enume- 
tated by Seringe f, throw but little light on the affinities of the 
groups of species; and it is only the painstaking and critical 
investigations of Fenzl that have advanced in any way our 
knowledge of this widely-distributed genus. Some objection 
may be raised to the sinking of Dolophragma, Fenzl, and Brachy- 
stemma, Don, in Arenaria: but the limitation of genera, in 
hatural groups like the order Caryophyllaces, requires a co- 
ordination of primary with secondary characters in an uniform 
manner in subordinate groups of genera, in order to preclude, as 
far as possible, the isolation of individual genera distributed 
sporadically in the guise of what are called (in some German 
systematic works) “ Mittelgattungen”; and such that the con- 
necting links in allied groups of genera should be in a radiating 
aud peripheral series, rather than in a linear and dichotomous 
wrie. Ina large natural order there are always a number of 
cycles of affinity which suggest groupings of genera, and the 
hore uniform in coincidence their limitation the less excuse 
there will be for the definition of aberrant types. 
The matter under the head of each species is arranged as 
follows. The name of the species is followed by the authority 
for the name and the work or memoir in which it was first pub- 
lished ; the second reference is to a general work or important 
fora, in which several species of the genus are enumerated or 
described, such as the first volume of Boissier's * Flora Orientalis,’ 
or the third volume of Willkomm and Lange's * Prodromus Flore 
Hispanicæ? Those species which were described before 1845 
* Bull. Herb. Boiss. iii. p. 593. 
+ Syn. Plant. i. p. 502 (1805). 
1 DC. Prodr. i. p. 401 (1824). 
