1 68 SCIENCE PROGRESS 



species B. maximus, remarkable for the small development of the wood, is 

 illustrated. 



The Conifers occupy some 200 pages of the Catalogue ; among them numerous 

 species of petrified wood of this class are described. The classification and 

 naming of Coniferous woods is admittedly one of the most difficult subjects in 

 palceobotany ; the author recognises seven genera, and, in accordance with views 

 now prevalent, attaches special value to the pitting of the medullary ray-cells as a 

 means of discrimination. It is pointed out, however, that all the seven are 

 " pseudo-genera," and are founded only for convenience of description. In 

 favourable cases the affinity with recent genera may be clear, as, for example, 

 between species of Pityoxylon and the Pines. The full and admirably illustrated 

 description of the anatomy of so many woods, including a number of new species, 

 appreciably widens the basis of our knowledge. 



Besides the woods, the petrified twig of a Sequoia, S. giganteoides, and the 

 beautifully preserved cones of Pinostrobus and Cedrostrobus are of special interest. 

 At the close of the section on Coniferales, a remarkable specimen from the Isle 

 of Wight, Vectia luccombensis, is described. It consists of a well-preserved tissue, 

 almost certainly phloem, attaining a thickness of 26 mm. and probably more. So 

 great a mass of phloem is almost unprecedented. The author inclines to regard it 

 as Coniferous, and suggests a comparison with Cryfitomcria, Thuja, and other 

 genera. To the reviewer it appears more probable that Vectia was the phloem of 

 a Cycadophyte, such as Bennettites, in which this tissue is known to have reached 

 a remarkable development. The structure of Vectia bears a sufficiently striking 

 resemblance to that of the phloem of Bennettites Gibsonianus (cf. fig. 73 with 

 fig. 10) to suggest affinity. 



Of the five species of Angiospermous stems described, two (Cantia arborescens 

 and Hythia Elgari) are new, while the rest have been recorded by the author in 

 a previous publication. All show perfectly typical Dicotyledonous wood-structure, 

 and have nothing primitive about them ; they also differ widely among them- 

 selves, showing that very diverse types had already appeared at this early date. 

 In no case can any certain conclusions as to affinities be drawn, though IVoburnia 

 shows agreement with Dipterocarpaceae ; the main point is the presence of highly 

 advanced and differentiated woody Angiospermous plants, while the "Age of 

 Gymnosperms " was still in progress. The origin of the Flowering Plants must 

 lie very far back. 



An appendix to the volume deals with some fossils, which, though found in the 

 Potton Sands, of Lower Greensand age, were probably derived from the Wealden. 

 They include two species referred to Cycadeoidea, Buckland, a genus commonly 

 taken as synonymous with Bennettites, Carruthers, but which the author regards 

 as distinct. On her view, the character distinctive of Cycadeoidea is the presence 

 of two or more zones of secondary wood in the trunk, while in Bennettites there 

 is a single zone. The two zones were mentioned by Buckland in his species 

 C. microphylla, but unfortunately the type specimens, both of this and of his 

 other species C. megalophylla, are lost. The species referred to Cycadeoidea in 

 the present volume are C. Yatesii, Carruthers, and C. buzzardensis, sp. now, with 

 numerous zones of wood. The fructification in both is unknown. 



The next plant described, Colynibetes Edivardsi, shows an extraordinary 

 structure, and well deserves its rank as the type of a new genus. The specimen, 

 of unknown origin, but probably from the " Potton Sands," consists of the inner 

 portion of a trunk, including the large pith and a considerable thickness of wood. 

 The pith, like that of other Cycadophytes, contains numerous gum-canals, and is 



