138 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 29, 



Descriptions of Fossil Plants from the Tarentaise. 



1. Neuropteris tenuifolia ? (Brongn. Veg. Foss. p. 241. t. 72. 



f . 3 ?) 



This is abundant, and some of the specimens are large, and tole- 

 rably complete. Leaflets very variable, even in the same specimen : 

 many of them agree well with the ordinary appearance of iV. tenuifolia, 

 as seen in the coal-fields of England, and as figured by Brongniart ; 

 but very often they are longer and narrower than in the normal state 

 of that plant, — sometimes so long and narrow that they might be 

 thought to belong to Pecopteris lonchitica ; while others again, on 

 the very same frond, agree almost exactly in outline with those of 

 Neuropteris flexuosa. I am inclined to refer the plant to N. tenui- 

 folia rather than to flexuosa, because the midrib is much more strongly 

 marked, and longer in proportion to the leaflets, than in normal spe- 

 cimens of the latter. The side-veins are very obscure in all the spe- 

 cimens, and this necessarily throws a doubt on the determination of 

 the species. There are many other variations, probably depending 

 on the distortion which the plants have undergone : sometimes the 

 leaflets are closely crowded, and even imbricated, sometimes remote ; 

 in some parts they lie almost flat along the rhachis, and again, in the 

 very same pinna, they are perpendicular to it, or even bent back. 



N. tenuifolia was described by Brongniart from specimens collected 

 in the coal-mines of Saarbriick. It has since been found in those of 

 Merthyr Tydvil and of Northumberland ; in the district of Osna- 

 briick (according to specimens in the British Museum) ; and in the 

 Permian formation of Russia. I am not aware that it has been ob- 

 served in America. 



2. Neuropteris gigantea? 

 Two or three detached leaflets, much resembling this species. 



3. Neuropteris? 



Fragments of very large leaflets with the venation of a Neuropteris, 

 apparently belonging to some species like N. ingens, or possibly to a 

 Cyclopteris. 



4. Odontopteris Brardii (Brongn. Veg. Foss. v. i. p. 252. 



t. 7o&y6). 



Fragments of this plant are numerous in the slates, and in many 

 of them, fortunately, the peculiar and characteristic venation is so 

 well preserved as to leave no doubt of the genus. The leaflets are 

 generally smaller and less acute than in the French plant figured by 

 Brongniart ; but there appears to be no difference of any importance. 

 None of the specimens however are sufficiently perfect to exhibit the 

 characteristic basal leaflets of the pinnae. O. Brardii appears to be 

 a very local fossil : there is no record of its having been found in the 

 joal-fields of England, Germany, or America ; nor indeed anywhere 



