360 CALAMITES. [CH. 



A transverse section of the axis of the cone in the region of 

 the sterile and fertile appendages shows the vascular bundles 

 arranged in pairs. In a section through the peduncle of the 

 cone, below the lowest whorl of bracts, the bundles of the stele 

 are situated at equal distances apart. The cortical tissue of the 

 peduncle is traversed by a ring of large canals^ similar to the 

 vallecular canals of an Equisetum stem. 



Isospory is not a constant characteristic of Palaeostachya ; 

 some forms have been found with macrospores and microspores^. 



Other Calamitean cones, and examples illustrating the connection 

 between Cones and Vegetative Shoots. 



It would be out of place in an introduction to Palaeobotany 

 to attempt an exhaustive account of the various cones which 

 were probably borne by Calamitean plants, but there are a few 

 general points to which the attention of the student should be 

 directed. The examples dealt with in the foregoing description 

 illustrate the fact, that plants included under the comprehensive 

 genus Calamites bore cones possessing distinct morphological 

 features. There are, however, other types of strobili which 

 have been found in organic connection with Calamites; and 

 some of these must be taken into account in dealing with 

 Calamarian plants. The genera Volkmannia, Brukmannia, Hut- 

 tonia, Macrostachya, in addition to Calamostachys and Palaeo- 

 stachya and others, have been applied by different writers to 

 Calamitean cones. As Solms-Laubach" has suggested, it is 

 wiser to discard Volkmannia and Brukmannia, as they have 

 been made to do duty for cones of widely different forms. 

 It is better to adhere to the provisional generic names used by 

 Weiss, as they enable us to conveniently systematise the various 

 Calamarian strobili. 



The following classification may be given of the better 

 known cones, some of which we are able to describe in 

 considerable detail, while others are still very imperfectly 

 known. We have good evidence that all these strobili were 



1 Williamson (882), pi_ vm. figs. 1 and 4. 



^ Eenault (93), PI. xxix. fig. 7. ■* Solms-Laubaoh (91), p. 325. 



