476 HYDROPTERIDEAE [CH. 



Some of the leaves figured as Tertiary Salvinias are of no value 

 as evidence of the former distribution of the genus^ 



From the Coal-beds of Yen-Bai (Tonkin), probably of Miocene 

 age, Zeiller^ has figured some well-preserved impressions of 

 oval or orbicular leaves, 15 mm. long and 10 — 20 mm. broad, 

 characterised by reticulate venation and by cordate bases, 

 which he refers to Heer's Swiss species Salvinia formosa^. 



Dr Zeiller* in the most recently published part of his series 

 of valuable resumes of palaeobotanical literature refers to a 

 description by Brabenec of specimens of this species from 

 Bohemian Tertiary beds showing both microspores and mega- 

 spores. 



One of the most complete specimens so far discovered has 

 recently been described by Fritel^ from Eocene beds of the Paris 

 Basin as Salvinia Zeilleri. This species, founded on portions of 

 stems bearing floating leaves, submerged root-like leaves, and 

 sporocarps, is compared with a recent tropical American species 

 S. auriculata. 



It is noteworthy that no authentic records of Hydropterideae 

 have been discovered in Palaeozoic rocks'. Comparisons have 

 been made in the case of the genera Traquairia Carr. and 

 Sporocarpon Will, with the reproductive organs of Azolla'', 

 but these rest on a wholly insufficient basis. 



Dawson^ proposed the generic name Protosalvinia for some 

 spores of Devonian age, which he regarded on inadequate 

 grounds as evidence of Palaeozoic Hydropterideae. 



Zeiller', in discussing the possible relationships of the 

 problematical tjrpe Chorionopteris gleichenioides Cord., suggests 

 a possible alliance with the Hydropterideae. Corda founded 

 the genus Chorionopteris^" on some small fragments of pinnules, 

 6 — 7 mm. long, found in the Carboniferous rocks of Radnitz in 

 Bohemia. 



^ E.g. Lesquerenx (78) PI. Lxtv. fig. 14 ; PI. v. fig. 10. Staub (87) PI. xix. 

 fig. 2. 



2 ZeiUer (03) PI. li. figs. 2, 3. 



3 Heer (55) A. Vol. iii. p. 156, PI. cxiv. figs. 1—315. 



« ZeiUer (09=) p. 95. » Fritel (08). 



8 See also Arber (06) p. 228. ' Solms-Laubach (91) A. p. 183. 



8 DawBon (86). » ZeiUer (88) A. p. 58. '» Corda (45) A. PI. mv. 



