Ser. RuoposperMEs. Fam. Spherococcoidee. 
Puate CCXVIII. 
RHODYMENIA PALMATAS vars. a and «. 
(For description, see last folio.) 
This and the preceding plate represent three forms of //o- 
dymenia palmata, the well known Dulse of the Scotch, and 
Dillisk of the Irish ;—and had I figured all the characteristic 
specimens which my Herbarium supplies, I might easily have 
extended the illustrations to a dozen plates. To connect Fig. 1. 
of Pl. CCXVII, with Fig. 3. of Pl. CCXVIII, by a full suite of 
specimens would require many figures. At first sight it will 
scarcely be supposed that they can belong to the same plant, and 
yet these figures by no means exhibit the extreme of variation, for 
there are varieties more simple than the one and more finely 
divided than the other. There is one state (var y. ) in which the 
frond is absolutely a simple elliptical leaf, without any division, 
or with a faint tendency to lobation at their apex. And there is 
another (var e.) which is occasionally cut into multitudes of many- 
cleft ribbon-like segments, in no place more than half a line in 
width. _ And yet these two forms can be clearly brought 
together by specimens of intermediate character. 
When such varieties are seen in a dried state in the herbarium, 
they appear so different that one may anticipate much difficulty in 
tracing the limits of the species. And it might indeed be 
difficult to do so with the assistance merely of dried specimens 
and of the descriptions of authors. But on the shore the collector 
experiences no such difficulty. If he has once seen and fasted a 
piece of Dulse, the characters, irrespective of form, are too well 
marked to allow of his puzzling himself with mere variations in 
outline. And what is very remarkable, the broad and slightly 
divided varieties may often be found growing side by side with 
the finely cut narrow ones. I have frequently noticed that where 
the Dulse grows on rock, it is broad and slightly divided; but 
when it grows on Fucus serratus, on the same rock, it is cut into 
the form called sodolifera. This would seem to prove that 
habitat had some effect, or, in other words, that the root of this 
