THE COMMON MOONWORT. 333 
barren branch with a three-parted instead of a single axis, its three 
branches in fact representing three small fronds of the ordinary state 
of the species. The lateral branches are rather smaller and less 
developed than the central one, thus producing an elongate deltoid 
outline, but the pinnules of all the branches are of the lunate or 
flabellate form characteristic of the species. It is hence no doubt a 
three-parted form of the common Moonwort; and it is curious to 
observe that the allied B. simplex, which in its more usual state has 
simple oblong barren branches, varies with the lower segments 
similarly developed into lateral branches, so as to produce tripartite 
fronds. It was found some years ago by Dr. Kinahan on Kilmashogue 
Hill in the county of Dublin, three plants being then found; two 
years later, on revisiting the spot, eight plants were observed having 
this peculiarity. Dr. Kinahan refers this curious variety to the 
eristatum series of variations, but it does not appear to us to present 
the peculiarities to which this term is applied among ferns, and we 
have therefore adopted the name tripartitum; he also suggests 
the possibility of this, instead of rutaceum, being the Lunaria minor 
. Jolüs dissectis of Ray, but we should rather identify our next variety 
with Ray's plant, than either this or the preceding. 
3. incisum (Milde). This form resembles the common state of the 
species in its general features, having the sterile branch oblong, and 
the pinne lunate; it differs in having the latter deeply incised 
so that their edges are cut into narrow segments. The plant is 
occasionally met with. Bolton records it from Halifax ; Lowe (vii. t. 
66 B.) figures it from Crosby Ravensworth under the name of Moorei ; 
and Dr. Kinahan records it from Kilnasantan, Dublin, under the 
name of laciniatum. It is however the var. incisum of Milde, and is 
well figured 1n the illustrations to his paper on the Cryptogamous 
Flora of Silesia. 

