364 Bower . — Studies in the Phytogeny of the Filicales. 
genus Blechnum remained otherwise still undivided. But in 1 809 Willdenow 
again divided the genus, which had meanwhile grown in number of species. 
Those with dimorphic leaves and with the sorus apparently marginal fell 
into the genus Lomarict , which was placed near to Struthiopteris ; those 
with their leaves conforming, and with their sori distinctly intramarginal, 
remained under the name of Blechnum , a genus placed in relation with 
Pteris and Vittaria on the one hand, and with W oodwardia on the other. 
Kaulfuss (1827) also kept the two genera distinct, but placed them side by 
side in his Blechnoideae. 
Presl in his Tentamen (1836) not only maintained the distinctness of 
the genera, but placed them widely apart in his system. He ranked 
Blechnum in his Tribe IV, Aspleniaceae, which included Cystopteris , 
Onoclea , Doodia , and W oodwardia , while he placed Lomaria in his Tribe VI, 
Adiantaceae, together with other genera now constituting the Pterideae. 
The distinction of the two genera thus recognized by Willdenow and 
accentuated by Presl was adopted by Sir William Hooker, and by Baker 
and various other writers. Sir William placed both genera under the 
heading ‘Lomarieae’ in the Species Filicum (vol. iii, p. 1), together with 
Sadleria, W oodwardia , and Doodia. But in the Synopsis Filicum, though 
the rest remain in his Tribe VII, Blechneae, he places Lomaria in the 
preceding Tribe VI of the Pterideae. It may further be noted that Onoclea 
(including Struthiopteris ) is far removed in Hooker’s system, being placed 
in his Tribe II, Dicksonieae. 
But already in 1856 Mettenius had expressed a contrary opinion (Fil. 
Hort. Lips., p. 60). He points out that the different forms of the fertile 
and sterile leaves are not a good criterion, since various steps between 
complete similarity and complete difference may be found. Neither is the 
position of the receptacle relatively to the midrib and margin a good 
criterion, for it may vary even in the different parts of the same leaf (Bl. 
Gilliesii , Taf. IV, Figs. 15, 16). These and other considerations led him to 
accept the position already stated by Schlechtendal (Adumbr. 34), that the 
genera Lomaria and Blechnum must be again thrown together. This con- 
clusion has been adopted by Luerssen (Rab. Krypt.-Fl., iii, p. m), by 
Prantl (Das System der Fame, 1892, p. 16), by Diels (Engler u. Prantl, 
i. 4, p. 245), and by Christ (Farnkrauter, p. 176, &c.). It is thus seen that 
the fusion of the genera is generally accepted, though it is still the custom 
to subdivide the genus into sub-genera, such as (1) Eu-Blechnum , (2) Salpi- 
chlaena , and (3) Lomaria . One of the objects of this investigation will be 
to test by developmental inquiry the validity of these conclusions. 
We have seen that Swartz placed his undivided genus^ Blechnum in 
near relation to Onoclea ( Struthiopteris ). Many of the later writers, after 
the division of the genus into Blechnum and Lomaria , placed one or the 
other, or both, apart from this affinity ; and the comparison, though early 
