CALAMARIEAE, 307 



Stephanospermum, Polylophospermum and Gnetopsis elliptica ; but he has 

 now 1 come to the conclusion that all the forms of Astromyelon are roots 

 of Calamodendron and Arthropitys, and that Astromyelon dadoxylinum 

 belongs to Calamodendron and A. augustodunense to Arthropitys. In 

 face of the evident stem-structure shown by his own figures, and which 

 it is scarcely possible to call in question, the botanist finds it difficult to 

 understand how such a view is possible. Its author himself says that the 

 general root-character can only be seen on young branches, and the reason 

 which he proceeds to give for his opinion appears, if I rightly understand it, 

 to rest on an assumption of the boldest kind. It would require some time 

 to examine into this assumption, and I am the less inclined to do so, 

 because it is before us at present only in the form of a sketch suited to the 

 preliminary communication in which it is contained, and it is therefore 

 hardly possible to avoid misunderstandings. 



The larger portion of the casts, which have long since been known by 

 the general name of Calamitae, belongs, as may be gathered from the 

 previous remarks, in part at least to the woody bodies known as Calamo- 

 dendreae. Another portion according to the French authors comes from 

 hypothetical plants resembling Equisetum, and having no growth in thick- 

 ness. The question at once arises whether it is possible to separate the 

 casts of the two kinds and how this is to be done, a question which engaged 

 the attention of Brongniart 2 himself, but which has been studied more parti- 

 cularly and in the widest extent by Grand' Eury 3 and Renault 4 . Grand' 

 Eury, after consideration. of all the circumstances, and relying especially 

 on his mining experience and on the mode of occurrence of the fossils, 

 answers the question in the affirmative, showing that there are firstly, casts 

 of Calamitae with a very thick rind of coal without striae on the surface, 

 and secondly, those in which the rind is no thicker than paper, so that 

 the striation on the cast appears even on the outside, though not so plainly. 

 The two types, still in the erect position, occur equally abundantly in the 

 quarries in the district of St. Etienne, of which he gives a sketch 5 . The 

 specimens of the first kind, Calamodendreae, are constantly found singly, 

 with their narrowed and fusiform extremities passing vertically through 

 the beds, and giving off from the nodes close whorls of long simple 

 descending roots 6 . Those of the other kind on the contrary 7 occur in 

 groups and converge below, and spring from erect or horizontal rhizomes ; 

 their conical base, either attached directly to the rhizome which bears them 

 or narrowed into a long thin thread-like basal portion, is always 8 bent round 

 a little to one side in the manner described above in the case of the bases of 



1 Renault (14). 2 Brongniart (2). 8 Grand' Eury (1), pp. u, 282. * Renault (2), 



vol. ii, p. 157. 5 Grand' Eury (1), t. 34. ' Grand' Eury (1), t. 31 ; Lindley and 



Hutton (1), vol. ii, tt. 78, 79. 7 Grand' Euiy (1), tt. 1-3. 8 Grand' Eury (1), p. 15, t. I, f. i. 



X 2 



