re 



* 



XL] PHYSEMATOPITYS 9 



an exception to the general truth of Essner's conclusions and that 

 the large dimensions and rounded form of the ray-cells are features 

 of diagnostic value, though in the Tertiary specimens compared 

 by him with the wood of Ginkgo the ray-cells do not appear to 

 differ appreciably in size or form from those of true Conifers. 

 Given well-preserved material, it is not improbable that in favour- 

 able cases the characters of fossil wood might furnish adequate 

 grounds for referring it to Ginkgo : the numerous obliquely ellip- 

 tical pits in each 'field,' the swollen medullary-ray cells, and the 

 frequent crossing of the pores of the tracheal pits are the features 

 mentioned by Gothan 1 who considers that the wood of Ginkgo 

 though difficult to define precisely in an analytical key may be 

 distinguished from that of Conifers. 



Among the specimens of wood assigned to Ginkgo there are 

 none, so far as I am aware, that can safely be accepted as entirely 

 above suspicion. In 1850 Goeppert 2 proposed the generic name 

 Physematopitys 3 for some Tertiary wood that he believed to possess 

 the anatomical characters of Ginkgo biloba. Kraus 4 subsequently 

 recognised resin-cells in the wood of Goeppert's type-species, 



hysematopitys salisburioides, and identified the specimens as the 

 root- wood of a Cupressinoxylon: he did not, therefore, include 

 Physematopitys in the list of woods contributed by him to 

 Schimper's Traite de Paleontologie, but mentioned it as a synonym 

 of Cupressinoxylon. Beust 5 and Barber 6 among other authors 

 adopt the same course. It has more recently been stated by 

 Krausel 7 that Goeppert's genus Physematopitys has the characters 

 of Protopiceoxylon. Goeppert 8 afterwards described a second 

 species, Physematopitys succinea, founded on a tangential section 



f a piece of Oligocene wood from the Baltic amber, but the 

 data are clearly insufficient to justify its identification as Ginkgo : 



onwentz 9 includes the specimen in Pinus succinifera. 



Schroeter 10 described some wood from beds on the Mackenzie 

 iver in North Canada, referred to the Miocene period, as Ginkgo sp. 



1 Gothan (05) p. 103. 2 Goeppert (50) p. 242, PL XLIX. figs. 15. 



3 (pua-rj/m-a, that which is blown out. 



4 Kraus in Schimper (72) A. p. 370; Kraus (83); Schenk in Zittel (90) A. p. 871. 



5 Beust (85). 6 Barber (98). ' Krausel (13). 



8 Goeppert and Menge (83) A. p. 32, PL x. fig. 74. 



9 Conwentz (90) A. p. 26. 10 Schroeter (80) p. 32, PL m. fig. 2729. 



