1877.] Fossil Plants of the Coal-measures. 413 



eguisetiforni Calamites in the shales of the Coal-measures, no one has yet 

 discovered a single fragment retaining its internal organization that does 

 not prove to be a so-called Calamodendron. He shows that the organization 

 of the latter specimens explains the minutest details of the common 

 impressions and casts found in the shales and sandstones of the Coal- 

 measures ; and hence he continues to hold his previous opinion that the 

 separation of the Carboniferous Calamites into two types is a fundamental 

 error, and unsupported by any justifying facts. 



M. Grand'Eury having disputed the lecturer's conclusions respecting the 

 structure of Aster oplmjllites, under the supposition that Sphenophylla have 

 been mistaken for examples of that genus, an additional example is pub- 

 lished, demonstrating that the long linear leaves were uninerved, and that 

 consequently the specimens could not possibly have been Sphenophylla, 

 the essential characteristic of that genus being that it is multinerved. 



Lepidodendron and Sigillaria. — The lecturer notices the continued sepa- 

 ration of these two genera by M. Grand'Eury and some other observers, 

 and especially the unintentional misrepresentation by M. Grrand'Eury of 

 the facts which lead the lecturer to recognize a very close relationship 

 between them. The only distinction which is supposed to exist, even by 

 the most earnest advocates, for making Lepidodendron a Cryptogam and 

 Sigillaria a flowering Gynmosperrn, is the presence, in Sigillaria, of an 

 outer exogenous vascular zone, in addition to the inner non-exogenous 

 one seen in all the Lepidodendra. M. Grand'Eury admits, in the most 

 definite language, that in all other features these groups of plants 

 possess exactly the same organization. The lecturer recalls attention to 

 the fact that in the Burntisland Lepidodendron, supposed to hoL. Velthei- 

 mianum, the exogenous zone is absent from the young twigs, but is gra- 

 dually developed in the twigs as they expand into branches ; hence, 

 according to the Brongniartian hypothesis, the plant is a Lepidodendron 

 in its young state, and a SigiUaria in its matured condition. Additional 

 illustrations are given from the stems of 'Lepidodendron selaginoides, the 

 species in which the exogenous zone is the least developed, of any of the 

 plants which possess such a zone, but which has no claim whatever, beyond 

 its possession of an exogenous cylinder, to be regarded as a Sigillaria. 

 The minute details of the structure of that zone, though feebly repre- 

 sented, exhibit, nevertheless, every essential characteristic of the same 

 zone in Sigillarian stems. These and other similar facts lead the lecturer 

 to adhere to his previous conclusions, and to regard the Sigillarim as 

 Cryptogams, representing only the highest forms of the Lepidodendroid 

 type of vegetation — conclusions to which some more recent investigations 

 of the Arran fossils, to be published in a future memoir, give the clearest 

 support. 



A very remarkable series of Lepidodendroid spores have been dis- 

 covered in the Halifax beds by Mr. Spencer and Mr. Binns. The most 

 abundant of these are microspores of the usual type associated with 



