AN EXTINCT PLANT OF DOUBTFUL AFFINITY. 437 



Slender axis bearing alternating whorls of bracts (14 to 

 20), cohering basably and free distally as long linear segments 

 extending- upwards through about six internodes. A single 

 verticil of long and slender sporangiophores on each whorl 

 of bracts. The sporangiophores bend inwards at the apex 

 and bear single sporangia. Isosporous. Spores with spinus 

 outgrowths. Probably the strobilus of Sphenophyllum 

 cuneifolium (Sternb). 



Sphenophyllostachys RoMERi(Solms-Laubach). Jahrb. 

 Geo/. Reichs. Wien, Bd. 45, Heft. 2, p. 225, Pis. ix. and x., 



i895- _ 



Axis and whorls of bracts similar to those of 5. Dazvsoni, 



except that in each verticil of bracts the free linear seg- 

 ments extend nearer to the strobilus axis. More than one 

 whorl of sporangiophores on each whorl of bracts, probably 

 three. Each sporangiophore forked distally, and bearing 

 a sporangium on the inwardly bent tip of each diverging 

 branch. Isosporous. Spores similar to those of 5". 

 Dawsoni. 



Genus Trizygia. Royle. Botany and Nat. Hist. 

 Himalayan Mts., p. 431, 1834. 



This generic name was proposed in 1834 for a genus of 

 plants occurring in the Glossopteris flora of India. 1 Little 

 is known as to its real affinities or structure, but Zeiller 2 

 has recently pointed out the doubtful generic value of its 

 characters, and he regards it as most probably a form of 

 Sphenophyllum. The slender stem bears verticils of wedge- 

 shaped leaves in three pairs at each node, the anterior pair 

 being smaller than the two lateral pairs. 



BIBLIOGRAPHY. 



Binney, E. W. Observations on the Structure of Fossil Plants in 

 the Carboniferous Strata. Palceontological Society, pt. ii., 1871. 



BRONGNIART, A. (i). Sur la classification et la distribution des 

 vegctaux fossiles en general, 1822. 



Brongniart, A. (2). Prodrome d'une histoire des vegetaux fossiles, 

 Paris, 1828. 



1 For figures see Feistmantel, pis. xi. A. and xii. A. 2 Zeiller (2). 



