294 Reports and Proceedings. 



that tlie stems were more advanced in. structure than those of 

 modern Equiseta, and enabled the author to explain the various 

 appearances presented by these plants, vrhen the external surface is 

 preserved, wholly or in part, and when a cast of the internal cavity 

 alone remains. It was further shown that the leaves of the ordinary 

 Calamites are linear, angular, and transversely wrinkled, and dif- 

 ferent from those of the Aster opJiyllites properly so called, though 

 some species, as A. comosus, Lindley, are leaves of Calamites. 



The Calamodendra, as described by Cotta, Binney, and others, 

 and further illustrated by specimens from Nova Scotia, and by 

 several interesting and undescribed forms in the collection of Prof. 

 Williamson, are similar in general plan of structure to the Cala- 

 mites, but much more woody plants ; and, if allied to Equisetaceae, 

 are greatly more advanced in the structure of the stem than the mo- 

 dern representatives of that order. Specimens in the collection of 

 Prof. Williamson show forms intermediate between Calamites and 

 Calamodendron, so that possibly both may be included in one family ; 

 but much further information on this subject is required. The 

 tissues of the higher Calamodendra are similar to those of Gymno- 

 spermous plants. The wood or vascular matter of the thin- walled 

 Calamites consists of multiporous cells or vessels, in such species as 

 have been examined. 



In conclusion, a Table was exhibited showing the affinities of 

 Sigillarice on the one hand, through Clathraria and Syringodendron 

 with Lycopodiaceae ; and on the other hand, through Calamodendron 

 with Equisetaceee ; while in the other direction they presented links 

 of connexion with Cycads and Conifers. 



Discussion. — Mr. Oarruthers expressed his thanks for the amount of information 

 given by Dr. Dawson, but was inclined to take a somewhat different view on some 

 of the points mentioned. Some time ago he had, in a paper read to the Society, 

 deduced from the internal structure of Stigmaria, the root of SigiUaria, that the 

 latter was a true oryptogamous plant. He had since met with confirmatory evidence, 

 in a specimen of a fluted and ribbed Sigillaria, showing the internal structure of 

 Stigmaria. Mr. Baily, in Devonian strata in Ireland, had found the root, stem, 

 branches, leaves, and fruit of a plant which could, with certainty, be correlated. 

 The root was a Stigmaria, the stem a fluted Sigillaria, the branches and leaves like 

 those of Lepidodendron, and the fruit that of a cryptogam, allied to Lepidodendron. 

 With regard to the American specimens cited by the author, he would not speak 

 with certainty ; but he might suggest a different interpretation. The axis was pro- 

 bably foreign to the Sigillaria in which is was found, and was a true coniferous stem 

 composed of pith, medullary sheath, and wood with medullary rays, and vascular 

 bundles passing to the leaves. Plants growing in the interior of decayed sigillarian 

 stems had been mistaken for organic piths, though they belonged to two or three 

 genera. Dr. Dawson's estimate of Calamites and allied genera essentially agreed 

 with those which he held. 



Dr. Dawson thought that the views of Mr. Carruthers and his own might possibly 

 be reconciled, but was not prepared to admit that the plant discovered by Mr. Baily 

 was a true Sigillaria. It belonged, moreover, to the Devonian period, and not to 

 the Carboniferous. He quite agreed with Mr. Carruthers in regarding the stems as 

 closely allied to gymnosperms. He insisted on the layer at the base of the interior 

 of the trunks of the erect Sigillaria affording evidence of the interior structure of 

 the plant, inasmuch as it consisted of the compressed and decayed inner tissues of 

 the tree. It was curious that similar specimens had not been found in England; but 

 the structures of these plants certainly occur in the English coal, which, like that of 



