BRITISH SEA-THRIFTS AND SEA-LAVENDERS. 69 
A. sibirica as sub-species under A. elongata; so that these 
authors appear to agree with Sir J. D. Hooker and Syme in their 
opinion of the insignificance of the value of the character which 
Boissier thought sufficiently definite to separate the genus into 
sections. Nyman, in his ‘Conspectus Flore Europee,’ pp. 614- 
616, however, follows M. Boissier’s arrangement, with the result 
that the two species, which by many authors are considered to 
be synonymous, are separated by five intervening species, 
A. pubescens beiug numbered 35 and A. maritima 41. 
So far as my limited observations of the European plants go, 
I have been surprised to find how readily this trifling character 
proved sufficient to separate the two groups, and, with the ex- 
ception of the British plants, the division does not appear to be 
unnatural. 
In the examination of a large number of British specimens, I 
also found this character more definite and stable than I ex- 
pected, and there was but little difficulty in referring the fruits 
of mature specimens to one or other of the varieties. In order 
to do this correctly care must be taken, especially with immature 
specimens from the herbarium, as sometimes, from the hairs on 
the ribs being pressed down, the appearance is given of the hairs 
being situated also upon the intercostal spaces. In such ex- 
amples it is a good plan to cut the fruit transversely and look 
down the intercostal spaces, when one can more readily deter- 
mine to which variety it belongs, and it is best to use a one-inch 
objective. Therefore my experience does not support Boswell 
Syme’s statement as to the instability of the character. The 
fruits vary considerably in hairiness, and it is well to bear in 
mind that the hairs are not soft and thin, but that they are stiff 
and relatively stout; also, that while a fruit may be thickly or 
thinly clothed with hairs, it dues not follow that the plant which 
has the fruits thickly covered with hairs on the nerves have them 
also on the intercostal spaces, nor does the fruit when the ribs 
are thinly covered with hairs have necessarily the interspaces 
bare. These bare spaces between the ribs are sometimes wide 
enough to allow of the character being observed by the naked 
eye. Distinct as the character appears to be, I am at present 
unable to correlate it with any other distinctive character; nor 
can T suggest that it is due to climatal, altitudinal, or geo- 
graphical cause, since both forms are found on the cold shoulders 
and summits of mountains, and on the face of sunny cliffs, both 
