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MR. RICHARD SPRUCE’S HEPATICE ELLIOTTIAN®. 351 
Other varieties are Dominica, Grande Souffriére (815, 838, 863, 
865, 868). 
This species, which is figured in Hooker’s ‘Musci Exotici, 
tab. 88, is represented by the largest number of specimens of 
any in Mr. Elliott’s collection. They were mostly gathered on 
the Grande Souffriére mountain in Dominica, and at the margin of 
“the Boiling Lake,” at an elevation of about 4000 feet, and are 
often thickly coated with sulphur and other mineral deposits. In 
colour they vary from nearly white to the sanguineous hue of 
var. purpurea, Hook. Bot. Mise. vol. i. p. 13, and in the degree 
of cutting of the leaf-margins from deeply dentate all round to 
nearly or even quite entire; but I fail to find any characters 
sufficiently constant to separate them into more than one 
species ; and the four “species” into which the Jsotachis of the 
Souffriére of Guadeloupe has been divided are to me unintelligible. 
It might, however, be interesting to whoever could spare the 
time and pains to trace out the varieties of this polymorphous 
species. 
In every Isotachis the outermost coat of the fleshy perianth is 
really the essential layer. It exists ab initio, and extends to the 
very apex at maturity. The inner layers, variable in number, 
vary also in height ; but all fail below the summit, which occurs 
rarely with a narrow free laciniate apex. I went over this 
question when I was describing Pleuroclada, a near ally of 
Isotachis, for my memoir “ On Cephalozia”’ (1882). The 
perianth, usually 5-8 cells thick below the middle (though 1] 
found one from the Swiss Alps only 3 cells thick), has exactly 
the same structure asin Isotachis, as I proved by cutting vertical 
sections of several perianths. Our commoner hepatics are apt 
to have the perianth abnormally thickened when they grow in a 
cool region, above their normal range. When this happens to 
Cephalozia bicuspidata, it becomes the var. alpicola of Massal. et 
Carestia, “‘ Epatiche delle Alpe Pennine” in ‘ Nuovo Giorn. Bot.’ 
xu. tav. 10. 
A very near ally of Zgotachis is the minute Jungermannia laxi- 
folia, Hook., of our northern rills, on which I founded the new 
genus Hygrobiella—so near, indeed, that I thought of making it 
a subgenus of Isotachis: the underleaves nearly equalling in 
size the bifid side-leaves, the lax elongate cells, such as exist in 
every Isotachis, the fusiform perianth, narrowed at the apex and 
nearly closed, triquetrous but not plicate, nor yet constricted by 
