basal vems distinguish the present species from other British 
Mitophylla. he nearest in affinity is certainly WV. versicolor, 
already figured in this work, from which the basal veins, and the 
proportionably smaller size of the cellules composing the mem- 
brane, together with some small differences, more easily seen 
than described, distinguish it. From WV. Gmelini, which it re- 
sembles in form, it is at once distinguished by the very different 
disposition of the tetraspores; from WV. Hillie, by the thimner 
substance, smaller size, and less mimute spots of tetraspores ; and 
from lV. punctatum, by the different outline of the frond. 
The specimens here represented, which are of the average size 
of those that occur on the west of Ireland, where this species is 
constantly found growing on the stems of Laminaria digitata, 
are less luxuriant than those figured by Dr Greville. They are 
quite as large, however, as any Devonshire specimens I have seen. 
No doubt, at Larne, where all the Mitophylla \uxuriate, so that 
the shore is pink with them, the present species reaches a much 
larger size. 
Fig. 1. NrropHyittum BonnEMAISONI :—with ¢etraspores. 2. A specimen pro- 
ducing tubercles ;—vatural size. 3. Portion of the frond, with a sorus. 4. 
tetraspores from the same. 5. Portion of the frond, with a tubercle. 6. 
Spores :—all more or less highly magnified. 
