BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S. 65 



which plates of a similar nature project towards the centre 

 partially dividing the longitudinal cavities, much like the divisions 

 in many reeds, canes, and grasses, except that they are not quite 

 closed. There are no leaves, properly speaking, but the shoots are 

 repeatedly divided with whorls of branches and branchlets at the 

 articulations. The fructification is in a terminal spike, consisting 

 of numerous closely packed peltate scales, bearing capsules 

 (sporanges) of one kind underneath, very much like the peltate- 

 fructification of Liverworts ( Marchantia). The sporanges are from 

 six to nine to each peltate scale of the fruit spike and they are 

 placed round the margin of the mushroom like top of the scale, 

 parallel with its stalk. The spores in the sporanges are very 

 minute and numerous, and they split when exposed into four 

 elastic filaments called elaters, which is what happens in the 

 Liverworts. 



This peculiar kind of jointed leaf is not unlike the Casuarina, 

 or sheoak of the colony, and the heads of fructification resemble 

 some Cycads, but the resemblance is merely external, for the plants 

 have little else in common. But on the other hand the natural 

 affinities of the plants are with Ferns, and the spores germinate 

 like them, producing a prothallus which bears archegones and 

 antheridia. The structure of the root and stem is very different 

 from that of Ferns. In an early stage there is a central column of 

 cellular tissue in the rhizome, from which eight plates radiate, 

 being connected with an external cylinder of the same nature, 

 having between them distinct cavities, which is the structure 

 observed in many fossil Calamites. But the vessels are annular and 

 not scalariform as in Ferns. 



The Horsetails are found in most parts of the world except 

 Australia and New Zealand. As a/ rule they grow in moist or 

 marshy places, but some flourish well in loose shifting sands, and 

 one is said to grow to a height of between 20 and 30 feet (E. 

 giganteum). They never reach the size of our fossil Horsetails. 



The closest resemblance exists between the fossil and living 

 genera. The mode of fructification of Calamites binneyi, Carr. is 



