This species is readily known from the common J/. Lamou- 
roux (Ner. Austr. t. 41), by its much narrower and nearly uni- 
formly narrow fronds, channelled throughout their whole extent, 
and of the same colour on both surfaces ; not conspicuously 
glaucous on the lower. It appears to be of rare occurrence, 
though received from two distant habitats. 
The genus Mastophora, founded by Decaisne, as a section of 
Melobesia, differs from Melobesia, more by the pliable and some- 
what coriaceous substance of the frond, and by the more branch- 
ing habit of the species included in it, than by any very defi- 
nite characters. The J/elobesie are evidently of a lower grade 
of organization than the Mastophore, which are, with one ex- 
ception, natives of the Southern hemisphere ; whereas d/elodesve 
are found in all parts of the world, many of them having indi- 
vidually a cosmopolitan distribution. 
Mastophora plana, Sond., found by Preiss in Western Aus- 
tralia, seems to be hardly distinguishable from some states of 
M. Lamourouen. 
Fig. 1. MastopHora CANALICULATA,—+the natural size. 2. Portion of the 
frond, lower surface. 8. Portion of the frond, upper surface, bearing con- 
ceptacles. 4. Section of the frond and a conceptacle. 5. Spore-threads :— 
the latter figures magnified. 
