56 CON I FERAE. 



the different formations, but it is in most cases doubtful whether they 

 belong to the Abietineae. It might indeed be maintained that there is no 

 real certainty except in the case of Pinus, and in that genus only when the 

 needles are connected together in their tufts. This does not appear to be 

 very frequently the case ; still it can be shown that species of Pinus with 

 bundles of two, three, and five needles lived in Europe during the Miocene 

 period, and that all except Cembra and Pinus canariensis have maintained 

 themselves to the present day in America only- side by side with the species 

 with two needles. From this fact and from the diffusion in circumpolar 

 regions of the Arvae, which seem to belong to older types of Abietineae, 

 is derived, as we know, the argument for the high antiquity of these members 

 of the American flora, and of that flora generally. Among examples of 

 well-ascertained species with five needles may be cited Pinites Palaeo- 

 strobus, Ett., 1 P. echinostrobus, P. fallax, P. Pseudotaeda, P. deflexa 2 ; of 

 species with three needles, Pinites Saturni, Ung. 3 , P. resurgens, Sap., P. 

 trichophylla, Sap., P. divaricata, Sap. 4 , all of the Tertiary epoch. It is more 

 or less probable that many other species were of similar character. 



The flat needles resembling those of the Silver Fir, which are frequently 

 recorded by authors from the Jurassic system upwards, and sometimes form 

 of themselves entire beds of coal (Abietites Linkii, Dk., from the Wealden 

 of Duingen, A. Crameri, Heer, from the beds of Kome in the Urgonian 

 formation of Greenland), may be properly passed over for the reasons men- 

 tioned above. It may be left to those who are working at the geography 

 of plants to put things in order here, which will not be done without 

 exact and systematic comparative examination of the epidermis of the leaf 

 in living and fossil forms. Schenk 5 has made this examination in the case 

 of the two species of Abietites just mentioned, and the result is that neither 

 of them can belong to Abietineae. Abietites Linkii, Dk. shows on the 

 under side of the leaf several rows of stomata-bands separated by broad 

 intervals and not lying on the two sides of a median nerve, somewhat as in 

 Podocarpus. A. Crameri has the stomata in the middle zone of the leaf, 

 Heer's median nerve, and none on the lateral parts of the leaf. In this 

 peculiarity and in the form of the epidermal cells the plant agrees exactly 

 with Sciadopitys, and Schenk therefore makes it the representative of 

 Sciadopitys in the period of the Chalk. 



A much greater amount of differentiation is presented by the great 

 series of Araucarieae, in which must be included the Sequoieae and Taxo- 

 dieae, if we accept the interpretation of the structure of the flower given 

 by Sachs and Eichler. The large generic groups with their marked differ- 

 ences of habit must be discussed one by one. 



1 von Ettingshausen (1) (Haring, t. 6, ff. 22-33), an d de Saporta (7), t. 3, f. i ; t. 4, f. 3. 

 de Saporta (8), t. 3. s Unger (1), tt. 4, 5. * de Saporta (8), t. 4. s Zittel (1), p. 293. 



