MATONIDIUM. 63 
pinnatifida. Nervi primarii excurrentes, secundarii angulo subrecto 
egredientes dichotomi, ramuli simplices. Sori biseriales oblongi 
indusiati. Sporangia receptaculo in ramulo affixa. Annulus 
obliquus.” 
When this fossil genus was first instituted by Schenk there 
was only one species recorded of the recent Matonia, and the 
characteristic and peculiar habit of that species, JL. pectinata, Br., 
suggested the term Matonidium for fronds of similar form. It 
is important, in speaking of this similarity of form and of the 
Matonia-like habit, to remember the recent addition of a second 
species, Jf. sarmentosa, Baker,! which has an entirely different 
habit to that which has always been regarded as typical of the 
genus. Baker’s figure of this new species shows in a striking 
manner the danger of trusting to sterile portions of fronds in 
the determination of generic affinity. 
1.—_Matonidium Gopperti (Ett.). 
1843. Cycadites Althausii, Dunker, Progr. p. 7. 
1846. Pecopteris Althausii, Dunker, Wealdenbildung, p. 4, pl. ii. fig. 2. 
Fecopteris polydactyla, Dunker, loc. cit. p. 5, pl. vii. fig. 4. 
Pecopteris Conybeari, Dunker, loc. cit. p. 7, pl. ix. figs. 8 and 8a. 
Alethopteris elegans, Dunker, loc. cit. p. 8, pl. vii. fig. 7. 
1849. Pecopteris polydactyla, Brongniart, Tableau, p. 107. 
Pecopteris Conybeari, Brongniart, loc. cit. p. 107. 
Pecopteris Althausii, Brongniart, loc. cit. p. 107. 
Pecopteris elegans, Brongniart, loc. cit. p. 7. 
1850. Pecopteris polydactyla, Unger, Gen. spec. plant. foss. p. 177. 
Pecopteris Conybeari, Unger, loe. cit. p. 177. 
Pecopteris Althausii, Unger, loc. cit. p. 176. 
Alethopteris elegans, Unger, loc. cit. p. 147. 
1852. Alethopteris Gépperti, Ettingshausen, Abh. k.-k. geol. Reichs. vol. i. 
Abth. ii. No. 2, p. 16, pl. v. 
1854. <Alethopteris elegans, Morris, Brit. foss. p. 2. 
1864. Pecopteris polydactyla, Leckenby, Quart. Journ. Geol. Soc. vol. xx. 
p- 80, pl. xi. figs. la and 10. 
1869. Laccopteris Gépperti, Schimper, Trait. pal. vég. vol. i. p. 582, Atlas, 
pl. xxx. figs. 5-8. 
1870. Pecopteris Althausii, Trautschold, Nouv. Mém. Soc. Nat. Moscou, 
vol. xili. p. 28, pl. xix. figs. 3d and e. 
? Pecopteris explanata, Trautschold, Joc. cit. p. 32, pl. xix. fig. 7. 
1 Annals Bot. vol. v. 1890-91, p. 191, pl. xiv. (First described in Journ. 
Linn. Soc. vol. xxiv. 1888, p. 256.) 
