352 



CALAMITES. 



[CH. 



coherent portion of each whorl. The manner of occurrence 

 of the whorls is shown in fig. 94, which has been sketched 

 from a large section in the Williamson collection. The seg- 

 ments of the successive sterile verticils alternate with one 

 another, so that in the surface-view of a cone the long and 

 narrow free bracts appear spirally disposed. Midway between 



Fig. 94. Calamostachys Binneyana (Carr.) in longitudinal (radial and tan- 

 gential) section. 

 Sp, sporangiopliores ; S, sporangia. 



(Prom specimen no. 1022 in the Williamson Collection, British Museum.) 



these alternating sterile verticils there is a series of fertile 

 appendages, also given oif in regular whorls. Each fertile 

 whorl consists of about half as many members as the segments 



