EQUISETITES. 31 



follows ] : " Radicibus tamen glandium simile oliquid scepe adkceret, 

 quot porcos credas requirere." De Candolle in his "Flore Fran- 

 gaise " 2 describes a new species, E. tuberosum, previously proposed 

 by Hectot, and specially characterized by the formation of tubers 

 on the lower nodes. In 1828 Bischoff 3 figured the tubers of 

 E. arvense attached to the rhizome. Among more recent authors, 

 in addition to Duval-Jouve, Milde 4 gives figures of tubers attached 

 to E. hiemale, L. 



Such tuberous internodes seem to have been unusually numerous 

 on the rhizome of Equisetites Burchardti, as is clearly shown by 

 the large numbers of attached and separate tubers in the English 

 Wealden beds. No other species of Equisetites affords such 

 numerous examples of tubers as this Wealden form, but a Tertiary 

 species, Equisetites Parlatorii, Heer, 5 should also be quoted as 

 characterized by its chains of elliptical tubers. Heer originally 

 described this species as Physagenia Parlatorii^ from Switzerland, 

 and recognized a probable relationship to E. fiurchardti he in- 

 cluded it, however, among the " Plantae incertce sedis" and, at the 

 same time, compared the " bladders " to the tubers of Equisetum 

 arvense, L., and other species. Schimper afterwards changed 

 Heer's name, Physagenia Parlatorii to Equisetum Parlatorii? 

 Another instance of fossil tubers is recorded by Heer from the 

 Jurassic beds of Amur, 8 under the name Equisetum Burejense, 

 Heer, and compared by him to the Wealden Equisetites Bur- 

 chardti. The same author has recorded another species with 

 tubers, E. arcticum, Heer, from the "Miocene" of Spitzbergen. 9 

 The gigantic Triassic Equisetites appear to have produced corre- 

 spondingly large tubers, e.g. E. arenaceum, Jaeg., and E. Munsteri, 

 Sternb. 10 



1 Hist. Stirp. indig. Helvet. vol. iii. p. 2 (under No. 1677, not 1676 as 

 stated by Duval-Jouve). 



2 Vol. v. p. 245. 



3 Die Chareen und Equiseteen, pi. iv. fig. 6. 



4 Mon. Equiset. pi. xxix. Nova Acta Ac. Cses. Leop.-Car. 1865, vol. xxxii. 



5 Heer, Fl. Tert. Helvet. vol. iii. p. 158, pi. cxlv. figs. 17-18. 



6 Ibid. vol. i. p. 109, pi. xlii. figs. 2-17. 



7 Trait, pal. veg. vol. i. p. 261. 



8 Fl. foss. Arct. vol. iv. p. 99, pi. xxii. figs. 6-7. 



9 Ibid. vol. ii. pi. i. figs 1-15. 



10 Schimper, Trait, pal. veg. Atlas, pis. ix.-xi. 



