610 STUDIES IN FOSSIL BOTANY 



Stachyotaxus, of Rhaetic age, has much in common 

 with Dacrydium, though in the fossil there are- two 

 seeds to each carpellary scale, instead of one. He 

 further suggests the possibility that the contemporary 

 Palissya, with five or six pairs of seeds on each carpel, 

 may be related, though he points out as an alternative 

 view that these genera may belong to an extinct race 

 of Gymnosperms, intermediate between Coniferae and 

 Cycadophyta. 



Coniferous wood, in a petrified, and especially in a 

 silicified condition, is among the commonest fossils of 

 the Mesozoic strata. Such specimens, for example, are 

 most abundant in the Lower Greensand and Wealden 

 of the Isle of Wight, and in the Purbeck beds 

 of Eastern Dorsetshire. Often, the preservation is 

 absolutely perfect, so that the finest details of histo- 

 logical structure can be studied. 1 Yet the results of 

 such investigations have so far been on the whole 

 unsatisfactory, and, however elaborately carried out, 

 have rarely, as yet, enabled us to determine with any 

 certainty the particular family to which a given Coni- 

 ferous specimen belonged. The recent investigations 

 of Dr. Gothan, 2 however, in which additional characters, 

 and especially the details of structure of the medullary 

 rays, are taken into account, give promise of more 

 definite results. 



The study of the fossil Coniferae is not yet suffi- 

 ciently far advanced for us to decide which of their 



1 See Barber, " Cupressinoxylon vectense," for an especially careful and 

 detailed examination of a Mesozoic Coniferous wood, Annals of Botany, 

 vol. xii. 1898. 



2 See W. Gothan, " Zur Anatomie lebender und fossiler Gymnospermen 

 Holzer," Abhandl. der h. Preuss. Geol. Landesanstalt, Heft 44, 1905. 



