BRITISH JUNGERMANNIiE. 
( J. Mackaii.J 
It is to my friend, Mr. J. T. Mackay, of the Botanic garden, Dublin, that we owe our first 
knowledge of this plant ; and to him I am anxious to dedicate it. Since this discovery, indeed, it 
has been found elsewhere in Ireland, as well as in England ; and, in the south-western part of our 
island, appears to be an abundant species on shaded and moist limestone rocks. In the numerous 
chasms in the ground, especially near the sea, about Torquay and Babbicombe, in Devonshire, 
J. Mackaii grows in such profusion, as to form a striking feature in the coloring of the perpendicular 
faces of the rocks : though it is in more exposed situations only that the delicate capsules are to 
be found, and, even there, not without an accurate examination, on account of their small size. 
The present species, although abundantly distinct, as well from J. dilatataasj. serpyllifolia, has, 
nevertheless, many characters in common with each. The former it approaches in general habit 
(though, perhaps, it has a still greater affinity in external appearance with J. complanata) , and in the 
figure of the calyx ; but it differs materially in the conformation of the lesser lobe of the leaf, in the 
white and delicate texture of the capsule, in the irregularly shaped greenish seeds, and in the double 
spiral filaments : — in all these particulars, and in the shape of the stipules, it so nearly accords 
with the latter (J. serpyllifolia), that a similarity in the shape of the calyx might not unreasonably 
be expected. But this is far from being the case ; for, in J. Mackaii, the calyx is depressed and has 
three angles ; whilst, in J. serpyllifolia, it is by no means flattened and is furnished with five angles. 
This affords a character the most decisive in enabling us to distinguish the two plants ; which may 
be further known, even upon a more casual inspection, by the much greater size, deeper, almost 
blackish-green, as well as the closer texture of the one ( J Mackaii ), when contrasted with the 
minuter foliage, more cellulose structure, and very pale green of the other ( J. serpyllifolia) . 
These peculiarities of the last mentioned plant are dwelt upon by Dr. Wahlenberg, in his admi- 
rable Flora Lapponica (a copy of which I have but lately had the opportunity of seeing) , under his 
J. cavifolia ; and it is from his having so done, rather than from his figure (in which no fructification 
is represented), or from his specific character, that I am induced to believe it to be the same as our 
J. serpyllifolia ; for both will accord equally well with J. Mackaii, as with that species. “ Colore,” 
he says, when speaking of J. cavifolia, £ ‘ lutescente et habitu J. complanata L. convenit, sed 
surculi triplo angustiores sunt fere in sequenti (J. trichomane) specie. Mollis est, et e reticulo 
grandiori facta.” 
