VASCULAR CRYPTOGAMS 21 



Vascular Cryptogams is so Convenient, that we have decided to adhere 

 to it, without dogmatising as to its permanent retention. In the 

 boundaries of the families, again, there is equal room for diversity of 

 opinion. Whether to retain the Psiloteae under Lycopodiacese, and 

 the Isoetese under Selaginellaceas, and whether to regard the true Filices, 

 the Marattiaceae, and the Ophioglossacese as constituting one, two, or 

 three classes, are points on which there is much to be said in favour of 

 classifications different from that which we have decided to adopt. 



Literature. 



Thuret— (Zoospores and Antherids) Ann. Sc. Nat., vol. xiv., 1850, p. 214; and 

 vol. xvi., p. 5. 



Hofmeister— Germination, Development, and Fructification of the Higher Crypto- 

 gams, Ray Soc, 1862. 



Schacht — Die Spermatozoiden, Braunschweig, 1864. 



Dippel— (Fibrovasc. Bundles) Ber. Deutsch. Naturf. u. Aerzte, 1865. 



Nageli u. Leitgeb— (Root) Nageli's Beitr. z. wiss. Bot., 1867. 



Kny— (Prothallium) Sitzber. Ges. Naturf. Freunde, Berlin, 1868. 



Millardet-(Prothallium) 1869. 



Russow— Vergleich. Unters., Petersburg, 1872. 



Janczewski- (Archegone) Bot. Zeit., 1872, p. 418. 



Goebel- (Sporangia) Bot. Zeit., 1880 and 1881. 



Sadebeck— Die Gefasskryptogamen, 1880. 



PrantI — Morphologie der Gefasskrypt. , 1881. 



Van Tieghem—Bull. Soc. Bot. France, 1883, p. 169. 



Potonie— (Vase. Bundles) Jahrb. Bot. Gart. Berlin, 1883. 



Leitgeb- (Spores) Ber. Deutsch. Bot. Gesell., 1883, p. 246. 



Celakovsky—Pringsheim's Jahrb. f. wiss. Bot., xiv., 1884, p. 291. 



Bower — (Leaf) Proc. Roy. Soc, xxxvii., 1884, p. 61. 



Rabenhorst — Crypt. Flora Deutschland, Vase. Crypt., by Luerssen, 1884-88. 



De Bary — Comparative Anatomy of Phanerogams and Ferns, 1884. 



Klein— (Dehiscence of Sporange) Bull. Soc. Bot. France, 1884, p. 292. 



Leclerc du Sablon — (Spores) Ann. Sc. Nat., vol. ii., 1885, p. 5. 



Campbell- (Antherozoids) Ber. Deutsch. Bot. Gesell., 1887, p. 120. 



Baker — Handbook to Fern Allies, 1887. 



HETEROSPOROUS VASCULAR CRYPTOGAMS. 



Class I. — Rhizocarpese. 



The Rhizocarpeae or Hydropteridese constitute a class composed of 

 only a small number of genera, none of which includes more than a few 

 species-. They grow submerged in or floating on water, and derive their 

 name from the circumstance that the non-sexual organs of propagation 

 are produced in the radicular region, or near the base of the leaves. 



