1848.] BUNBURY ON FOSSIL PLANTS. 139 



(in the old coal formation) except in the mines of Lardin, near Ter- 

 rasson, in the department of the Dordogne. 



5. Odontopteris obtusa? (Brongn. Veg. Foss. p. 255. t. 78. 



f. 3&4). 



Of this I observed some very incomplete fragments, entirely agree- 

 ing with Brongniart's" figure and description of O. obtusa ; but other 

 and more numerous specimens are exactly intermediate between his 

 O. Bi'ardii and O. obtusa, or rather exhibit the characters of both 

 together. In the best-preserved specimen, the leaflets are strikingly 

 different on the opposite sides of the same pinna : on the one side 

 they are short, almost round, or rather broader than long, and very 

 obtuse, much resembling those of O. obtusa in Brongniart's fig. 4. 

 t. 78 ; on the other side they approach closely to the normal form 

 of O. Brardii. This singular incongruity is most strongly marked 

 towards the base of each pinna, the leaflets towards the extremity 

 becoming gradually more and more symmetrical, and, at last almost 

 wholly so. It is possible that the want of symmetry may be pro- 

 duced in part by distortion, for the leaflets are dissimilar in direction 

 as well as in form. The venation in this particular specimen is beau- 

 tifully preserved, and thoroughly characteristic of the genus Odon- 

 topteris. 



Other fragments exhibit the dissimilarity of the leaflets in a greater 

 or less degree, with a variety of intermediate forms ; and, with every 

 reasonable allowance for distortion, they lead me to the conclusion 

 that the Odontopteris obtusa (of which small fragments only have 

 been hitherto observed) is merely a variety of O. Brardii. 



The localities assigned by Brongniart to the Od. obtusa are, Lar- 

 din, near Terrasson (where it was found in company with O. Brardii 

 and O. minor) y and the Col de I'Ecuelle, near Chamounix. This latter 

 locality belongs to the ambiguous formation of which I am here 

 treating. The Od. obtusa of Lindley and Button's * Fossil Flora' 

 (from the Shropshire coal-field) is considered by Goppert as a di- 

 stinct species, which he calls O. Lindleyana. 



6. Pecopteris Cyathea (Brongn. p. 307. t. 101). 



Specimens well characterized, and referable with tolerable certainty 

 to this species, or rather perhaps to the variety called P. arborescens. 



Pecopteris Cyathea appears to be one of the most generally dif- 

 fused of the fossil ferns of the coal-measures. It has been observed 

 in the coal-fields of Saxony, Bohemia and Silesia ; at St. Etienne, and 

 various other localities in France ; near Osnabriick ; in many of the 

 English coal-fields, and in most of those of North America. In this 

 enumeration I include the localities of the so-called P. arborescens, 

 as I find it impossible to distinguish between the two forms. 



7. Pecopteris ? 



A fern very like P. Cyathea, but with larger leaflets, of a rounder 

 form, and remarkably broad in proportion to their length. Main- 

 stalk excessively thick. Venation not distinguishable. 



vol. v. part I. L 



