is, however, only short. This mode ol' venation distinguishes it also from the 
genus Ctenopteris. The form of the leaflets, as well as the venation, distin- 
guish it in a like manner from Pachypteris, Bgt., and Dichoptcris, Zigno, 
both of which, it appears, arc in close relation to each other. There is, 
therefore, only the genus Thinnfeldia into which this Australian plant can 
he best placed, especially if we compare the figured specimens of Mr. Car- 
ruthers (loc. cit., PI. XXVII, Pigs. 2, 3), of Mr. Crepin ( loc . cit., Pigs. 
1-4), and those of myself (loc. cit., 1378, PI. XV, Pigs. 5-7, and PI. XVI, 
Pig. 1, or now PI. XXVI, Pigs. 1, 2, and IT. XXIX, Pigs. 1, 5), with the 
figures of Prof. Geinitz’s Thinnfeldia crassinervis .* This also shows dicho- 
tomy of the leaf, similar leaflets, and a similar venation. 
I have figured a good number of specimens from various localities ; 
in several cases they differ in the size of the leaf, and also of the leaflets; in 
some instances also apparently in the venation, hut if thoroughly compared 
it will he found that all the various leaf varieties belong to the same species. 
The diagnosis of this species given by me, in 1879, was as follows : — 
“ Prondc magnitudine variante, nunc tenera, mediocri, nunc robusta, valida ; 
simplici an dichotome divisa ; frondibus quse, simplices sunt, pinnato- 
pinnatifidis ; pinnis longis ; pinnulis rliombeo-ovatis bine illine indentatis, 
basi connatis imis basalibus rliachi frondis insertis, semiellipticis, sed sequente 
cum pinnula connectis. Prondibus quse dichotomic sunt, pinnatifidis an 
pinnato-pinnatifidis ; pinnis in portione indivisa locoque divisionis proximis, 
brevioribus ; illis in ramis longioribus ; pinnulis variantibus nunc oblique 
ovato-oblongis, nunc quadrato-ovatis, integris, an apice oblique truncatis an 
indentatis ; in fronde pinnato-pinnatifida pinnulis imis basalibus etiam remotis 
et, in pinnis superioribus, rachi frondis adflxis ; nervis partim ex uno, quasi 
mediano, media in parte basis ex rliaclii eggrediente, furcatione repetita 
orientibus, nonnullis aliis directe ex rliachi eggredientibus, etiam furcatis.” 
In this diagnosis all the various forms of this -species are included. 
According to it this species was of various sizes, now slender and of middling 
size, another time large and of strong growth ; this depends, apparently, upon 
the age of the plant ; the leaf is either simple or dicliotomously divided. 
The simple fronds are pinnate-pinnatifid ; pinnae long ; pinnules rhomboid 
ovate, here and there dentate on the upper margin, at the base they are 
* Palaeontograpliica, Suppl, III, Lief. II : Rhat. Pflanzen void Thierreste in den Argentinisclien Pro- 
vinzen, Tab. I, Figs. 10 -16. 
