42 
The most distinct is acutum, which is a remarkably elegant plant ;— 
chiefly found in Ireland and in the western counties of England, and 
seems rare.— Handbook of British Ferns, p. 158, date 1853. [I men- 
tion this work simply from a feeling of courtesy, as it would not be 
right to pass over a notice in which my late friend Bory’s authority 
and my own are cited. It must, however, be observed that the plant 
has not been recorded as growing in England, and that Mr. Moore’s 
figure evidently represents the commoner species. I cannot, there- 
fore, regard Mr. Moore as expressing any opinion on the specific 
identity of a fern with which he appears to be unacquainted. ] 
Botanical. 
First.—It appears to me that Dillenius, Smith, and Francis exer- 
cise sound botanical discretion in refusing to establish a species on 
the faith of a single frond, and that barren, and grown in a dark cave. 
In these three facts we cannot fail to see strong reasons against such 
a course. But, while admitting the justice of the conclusions which 
these botanists draw from the very scanty materials within their reach, 
we must place greater confidence still in the conclusions which Bory, 
Willdenow, Sadler, Sprengel, Presl, and Wellwitsch have agreed in 
drawing, from materials the most perfect and complete that could be 
desired. Just in proportion as it was right to reject such scanty evi- 
dence, so would it be absolutely absurd to weigh the conclusions 
drawn from that single barren frond against those founded on copious 
series of mature, normal, and highly fructified fronds. Itis worthy of 
especial observation, that Bory, Willdenow, and Sadler calmly and 
philosophically consider the hypothesis of uniting the two species, 
and, assisted by their abundant materials, unhesitatingly reject it. 
Sprengel, Pres], and Wellwitsch do not even entertain the question. 
The argument that the peculiarities of the fern are due to situation, or 
want of fruit, falls entirely to the ground when we learn that such con- 
ditions were purely exceptional. Dr. Allmann’s opinion is, however, 
of great value, and is not liable to the objection of being formed on 
insufficient data. It is noticed again below. 
Secondly.—The occurrence of the same plant in Teneriffe, Madeira, 
Portugal, Spain, Italy, Illyria, and Hungary,—countries in most of 
which Adiantum-nigrum occurs, and has never been confounded with 
it,—is a primd facie argument in favour of its distinctness. 
Thirdly.—In Irelayd, also, it is additional to Adiantum-nigrum, 
instead of replacing it: Adiantum-nigrum is common ; acutum, local, 
and noticeable as a comparative rarity. 
