248 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 1G, 



2. Neuropteris Jlexuosa, Ad. Brongn. After the examination of a 

 great number of specimens of this, from Somersetshire, Savoy, Spain, 

 Pennsylvania, and Cape Breton, I am unable to satisfy myself whether 

 it be permanently distinct from N. gigantea. They are indeed in 

 general easily enough distinguished by the form of the base of the 

 leaflets, which in N. Jlexuosa is more oblique and less symmetrical than 

 in the other, with its lower margin extended into a decided angle or 

 auricle, while the upper one is rounded off. The wavy main stalk is 

 also a usual characteristic of N.Jlexuosa. But both these characters 

 vary in degree, and I have seen specimens in which they are quite 

 ambiguous. The character on which Brongniart lays so much stress, 

 that of the closely-placed overlapping leaflets, is (as I long since 

 remarked) by no means constant. Whether the N. gigantea and N. 

 Jlexuosa be truly distinct or not, they seem to have inhabited differ- 

 ent localities, for I am not aware that I have in any case seen well- 

 characterized specimens of both from the same coal-field. As they 

 may in general be pretty easily distinguished, though intermediate 

 forms do now and then occur, it will be convenient for the present 

 to keep them separate. 



M. de Verneuil lately showed me specimens of N. jlexuosa from 

 the province of Palencia (in the kingdom of Leon), Spain. It seems 

 to be most abundant in the coal-mines of North America. The only 

 well-characterized British specimens that I have seen are from the 

 Somersetshire coal-field, and from that of Pembrokeshire ; while, on 

 the other hand, the N. gigantea seems to abound particularly in the 

 Midland coal-fields of England. 



3. Neuropteris rotundifolia, Ad. Brongn. I cannot but believe 

 this to be a mere variety of N. Jlexuosa, as I have seen on the very 

 same fragment leaflets corresponding with the characters of both. 

 The analogy of innumerable instances among recent Ferns (ofPteris 

 rotundifolia, Swartz, for one) shows us how little importance ought 

 to be attached to such variations in the outline of the leaflets as those 

 on which the distinction of these two species is founded. At any 

 rate, the N. rotundifolia is much too doubtful a species to be of any 

 value as a geological characteristic. Nor, with respect to locality, is 

 it peculiar to the Calvados ; there is a good specimen of it from 

 Northumberland, in the museum of this Society. 



4. Neuropteris rarinervis, C. Bunbury (Quart. Journ. Geol. Soc. 

 vol. iii. p. 425.). 



I suspect that this species is not uncommon, and that it has often 

 been confounded with N. tenuifolia. The two are certainly much 

 alike ; but, if we may trust to the figure and specific character of N. 

 tenuifolia in Brongniart' s great work, they differ materially in their 

 veining. Some of the specimens labeled N. tenuifolia in the Society's 

 collection, namely those from Merthyr Tydvil, seem rather to belong 

 to N. rarinervis ; and I am inclined to refer to the same species some 

 fragments that I possess from the district of Osnabriick. If this 

 plant be compared on the one hand with N. tenuifolia, and on the other 

 with the Pecopteris (Cladophlebis) pteroides, we shall see how they 

 connect together the two artificial genera Neuropteris and Pecopteris, 



