1898] SOME NEW BOOKS 275 



there is no absolute certainty that any of these so-called palaeozoic 

 Equiseta are identical with the recent genus, he probably takes the 

 right course. Among those described are Equisetitcs Etemingivayi, 

 Kidston sp. ; Equisetites spatulatus, Zeillei ; E.culumnuris, Brongt.; and 

 E. lateralis, Thill. The consideration of Phylloiheca and Schizoneura 

 lead us up to the Calaniites — which is one of the most important 

 groups — (for it cannot be considered a genus in any true sense of the 

 term) — of palaeozoic times. 



The study of the Calamiles is introduced by a historical sketch, 

 and this is succeeded by a description of the anatomy of the stems, 

 leaves, roots, and cones, each of which is illustrated by good figures. 



This class he treats with great skill and shows a complete mastery 

 of a very difficult subject. He recognises three types of Calamite 

 stems as determined from internal structure: — 



Arthropitys, which is the type commonly met with in the Lanca- 

 shire and Yorkshire Coal Fields. 



Artlirodendrun, which is very rarely met with in Britain. 



Calamodendron, which hitherto has not been recorded from Britain. 



The structure of the leaves is next given, after which follows a 

 description of the Calamine genera that are founded on impressions. 

 These are: — Calamocladus (Astcrajd(>///ites), of which Calaiaocladits 

 equisetiformis is fully described as a typical form. This is succeeded 

 by a description of Annular to, A. stellata and A. sphe/iophylloides 

 being given in full detail. The roots of Calamites are next dealt 

 with, and with them is now associated the Astromyelon of Williamson. 



Three types of Calamitic cones are described. These are Cala- 

 mostachys (with which is united Stachannularia) ; Palaeostachya and 

 Macrostachya. Huttonia is also referred to, but with the exception of 

 the first two genera, little is known of their internal structure, with- 

 out which their true position cannot be satisfactorily determined. 

 Much still recpuires to be done in the elucidation of Calamitic cones 

 and great care must be exercised in forming opinions as to their 

 affinities. 



The impressions and casts of stems are now considered and are 

 classed under the three sub-genera of Weiss : — Ccdamitina, Stylo- 

 calamites and Eucalamites. The study of Calamite stems presents 

 considerable difficulty. Many specimens which have been regarded 

 as stems are certainly only the casts of the pith cavity, but others, 

 such as many Calamitina show the outer surface of the stem. These 

 three sub-genera are distinguished by the manner in which the branches 

 were borne on the stems — a system of classification which can only be 

 regarded as provisional, in very few cases can the foliage and cones 

 be associated with their parent stem. 



Archaecalamites, from the Lower Carboniferous and Devonian, forms 

 another group, which is closely related in some of its characters to 

 Calamite*, but is clearly separated from that genus by several 

 important differences in the stein and cones. 



Chapter xi., which concludes the volume, is devoted to the 

 Sphenophyllales. 



As in the previous groups the structure of the stem of SjpTienophyU 

 lum is first descrihed. Owing to the numerous specimens of Sphcno- 

 phyllum which have been discovered showing fine structure, the develop- 



