38 VASCULAR CRYPTOGAMS 



Plants. The sporocarps of M. Drummondii (Br.), and probably of some 

 other species, are eaten- by the natives of Australia under the name of 

 nardoo. 



Literature. 



Bischoff — Die Rhizocarpeen unci Lycopodiaceen, Nuremberg, 1S28. 



Mettenius— Beitr. zur Kenntniss cier Rhizocarpeen, 1846; Linntea, 1847, p. 260; 



and Beitr. zur Botanik, Heft I, 1853; Plantae Tinneanae. 

 Meyen — Nov. Art. Acad. Caesar-Leopold., vol. xviii. , pt. i, p. 253. 

 Hofmeister— Ueb. Keimung der Salvinia, Abhandl. Sachs. Gesell. Wis?. 1857, 



p. 665. 

 Pringsheim— (Salvinia) Jahrb. f. wiss. Bot., vol. iii., 1863, p. 484. 

 Hanstein— Ueb. eine neuhollandische Marsilia, Monber. Berl. Akad., 1862, p. 183 ; 



Befruchtung u. Entwickelung der Marsilia, Jahrb. f. wiss. Bot., vol. iv., 1865, 



p. 107 ; Pilularice generatio cum Marsilia comparata, Bonn, 1866. 

 Braun— (Marsilia and Pilularia) :\Ionber. Akad. Wiss. Berlin, 1870, p. 653, and 



1872, p. 668. 

 Russow — Vergleich. Unters., Petersburg, 1872 ; and Hist. u. Entwick. d. Sporen- 



frucht V. Marsilia, Dorpat, 1877. 

 Strasburger— Ueber Azolla, Jena, 1873. 

 Juranyi — Ueb. d. Entwick. d. Sporangien u. Sporen v. Salvinia, Berlin, 1873 ; and 



(Pilularia) Sitzber. Ungar. Akad. Wiss., 1879 (see Bot. Centralbl., vol. i., 1881, 



p. 207). 



Berggren — (Azolla) Rev. Sc. Nat., 1 88 1, p. 21. 



Heinricher — (Sporesof Salvinia) Sitzber. Akad. Wiss. Wien, vol. Ixxxv., 1882, p. 494. 



Goebel — (Pilularia) Bot. Zeit., 1882, p. 771. 



Class II.— Selaginellaceas. 



This class is composed of two genera only, Selaginella (Spring) and 

 Isoetes (L.), resembling one another in the general facts of their life- 

 history, but differing widely in external appearance, and each consti- 

 tutmg a monotypic order. We have, again, as in Rhizocarpeae, two 

 kinds of spore; the megasporanges and microsporanges are of very 

 similar appearance, and are produced in connection with the leaves. 

 The female prothallium, produced within the megaspore, is a more 

 completely endogenous structure than in any other class of Cryptogams, 

 and is altogether destitute of chlorophyll. From the occurrence in both 

 genera of a foliar structure known as the lignle, the term ' Ligulatae ' 

 is sometimes given to the class ; but the character is unsatisfactory, 

 and it will be best to treat the two orders Selaginellece and Isoctece sepa- 

 rately. 



