220 BEACHTPHYLLUM. 



I believe we cannot sufficiently discriminate between the several 

 specimens figured by the above authors, and the similar fragments 

 from the English Wealden strata, to arrive at any trustworthy 

 specific distinctions or diagnoses of well-marked specific types. 

 To group together all these forms may be unwise, and it has 

 already been pointed out that we find certain points of difference 

 between some of the specimens, which suggest ^either specific 

 distinctions or varieties of the same type. I venture, therefore, 

 to make use of Heer's specific name B. olesum in a somewhat 

 more comprehensive sense than has been adopted by Saporta. 



Among recent conifers, e.g. Cupressus Lawsoniana, Parl., etc,, 

 we find a considerable difference in the appearance of the branches 

 depending on the development of numerous or few lateral branches 

 in the axils of the leaves ; we have the closely set lateral branches 

 as in some forms of B. crassicaule, as figured by Fontaine, and 

 the more elongated branches without the closely set lateral shoots, 

 as in B. olesiforme var. elongatum, Sap. To unite such forms under 

 one name, especially in the absence of cone-bearing branches, can 

 hardly be regarded as an unwarranted extension of the limits of 

 a fossil species of which our accurate knowledge is extremely 

 small. The Jurassic species Braehyphyllum gracile, Brong., 1 appears 

 almost identical with some forms of B. olesum ; such comparisons 

 might, however, be considerably increased, but without leading 

 to any satisfactory conclusions. 



Many of the specimens referred to B. olesum agree very closely 

 with B. spinosum, sp. nov., and it is, I believe, almost impossible 

 to feel much confidence in our attempts to distinguish between 

 small specimens of plants of this particular form. Possibly it 

 would have been better to make use of Fontaine's specific term 

 crassicaule for some of the following examples, and to have 

 included others under B. olesum ; but if we examine such a series 

 as is represented by the following specimens, the difficulty of 

 accurate determination becomes apparent : V. 3348 (PI. XVII. 

 Fig. 9), V. 2137 (PL XX. Fig. 1), V. 2137 (PI. XX. Fig. 2), 

 V. 2337 (PI. XX. Fig. 4). 



V. 2137. PI. XX. Fig. 1. 



Cf. Bracliyphylliiiii olesiforme var. elongatum, Saporta, pi. xxxi. 



1 Saporta, Pal. Franc?, vol. iv. p. 365, pi. clxviii., clxx., and clixi. 



