CALAMARIEAE. 325 



brought close to one another, the surface only can be seen, if the arrange- 

 ment is looser, the organisation also can be examined, but usually much less 

 perfectly than in the petrified specimens. Owing to this difference in the 

 mode of preservation and also to the general similarity of habit, the identi- 

 fication of the several specimens with one another is difficult and uncertain. 

 Premature and misplaced attempts of this kind are among the chief causes of 

 the distracting nomenclature and synonymy, which is nowhere a more serious 

 hindrance to the study of the forms than it is in this case. The old names 

 especially, Volkmannia, Stbg, Bruckmannia, Stbg, have been differently in- 

 terpreted by almost every later author, and have been connected with various 

 recently discovered types. It will conduce to a better understanding, if with 

 Weiss 1 we discard them altogether. It is certain that a final system of classi- 

 fication and nomenclature is at once excluded by the fragmentary character 

 of our knowledge of all these remains, and that our only object must be to 

 frame provisional groups, which, corresponding to the state of our knowledge, 

 may afford a general view of the facts as they have been ascertained. Weiss' 

 arrangement secures this advantage in a high degree by refusing to make 

 every difference though not unimportant in itself the occasion of a new 

 name, and by attending only to the ground-plan of the structure ; we will 

 follow it therefore in our subsequent remarks. 



With the exception of a few remains of abnormal character which will 

 be considered at the end of the chapter, the spikes of Calamariae are all 

 cylindrical in form and more or less thickly covered with leaves, while there 

 is much difference in the relative size of the parts. Wherever it has been 

 possible to examine them, they have been found to be composed of fertile 

 and sterile whorls of leaves which succeed one another in regular alternation. 

 The sterile whorls usually consist of a considerable number of lanceolate 

 sharply-pointed leaves, which are either free or united together by a larger 

 or smaller portion of their bases, the free apices being bent upwards in such 

 a manner as to lie like tiles on the leaf-bases of the whorl next above them of 

 the same description, and to arch over the interposed fertile leaves, being thus 

 the only ones seen in the surface-view of the whole fructification. The 

 fertile leaves are usually, as in Equisetae, not united together, and are 

 furnished with an umbellately peltate lamina, which bears the sporangia on 

 the under side. According to the relative position of the two whorls to one 

 another Weiss distinguishes the types Calamostachys and Palaeostachya, to 

 which latter Huttonia is attached. The entirely provisional names Paracala- 

 mostachys and Macrostachya are applied to spikes of imperfectly ascertained 

 structure, in order to k connect them with one or the other type, Macrostachya 

 including the forms which in habit resemble forms of Palaeostachya. To 



Weiss (5). 



