ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 53 



species as shown by the size of the plants and their success in pollination, 

 seed-distribution, etc. All formations are characterized biologically by 

 the number of predominating vital forms — that is, those forms which are 

 most perfectly adapted to their habitat ; physiognomical ly by those 

 forms of predominating mass. By adopting a series of vital forms as 

 the basis of a system of classification, there is found to be a definite 

 progressive perfection of adaptation corresponding with a diminution in 

 physiognomic predominance. In conclusion, the author draws up a 

 scheme for a scientific description of plant formations. This scheme 

 ■comprises eight classes, each of which consists of plants of a similar 

 habitat, e.g. Hydrophytes, Halophytes, etc. The classes are then sub- 

 divided according to such species as deciduous or evergreen leaves, 

 rooted or free-floating habit, etc. It is also, pointed out that ecologic 

 ■descriptions must be based upon an intimate knowledge of the soil from 

 ohemical, physical and biologic points of view, as well as upon the 

 characters of the plants under morphological, anatomical and physical 

 aspects. S. G. 



CRYPTOGAMS. 



Pteridophyta. 



Mazocarpon, or the Structure of Sigillariostrobus. — Margaeet 

 J. Benson {Annals of Botany, 1918, 32, 569-89, 2 pis. and figs.). A 

 description of fossil specimens of Mazocarpon, its cone, sporophylls, 

 sporanges, megaspores, and a discussion of the grounds for identifying 

 Mazocarpon with Sigillariostrohus. Mazocarpon is a sporangial appa- 

 ratus of the Lycopsid type. The cone bore close spirally arranged cone- 

 scales of the Lepidostrohus ground plan, but constricted at the plane of 

 attachment to the axis ; the cone-scales were exceptionally caducous. 

 There is no free lamella directed downwards, but a convex thicker portion 

 without a ridge may extend to about • 8 mm. below the plane of the 

 keel of the proximal part of the bract (cone-scale). The distal erect 

 part tapers from 6 mm. in width to a point at not less than 6 mm. above. 

 The sporangia are characterized by the possession of much sterile per- 

 sistent tissue and the proliferation of the distal wall beyond the limit of 

 the attachment of the sporange to the bract. In the megasporange 

 this lamella is shovel-shaped, and fits into the adaxial concave surface of 

 the upturned part of the bract. The megaspores do not exceed eight 

 and germinate in situ, while the spore-wall is plastic. The organic apex 

 of each so-called " spore " is directed centroscopically with reference to 

 the' sporange. 



There is considerable range of form, determined by the position 

 which the germinating " spore " occupies in the space between the 

 sporange-wall and the subarchesporial pad. The form of those occupy- 

 ing the wider distal end of the sporange in M. Shorense tends to be that 

 ■of a shallow crucible with the organic apex in the hollow, but many 

 asymmetric forms occur. The spore-wall bears pointed prong-Hke teeth 

 •over its convex base — i.e. the surface directed towards the wall of the 

 «porange. The cone is pedunculate. The sectional area of cone-axis 

 and peduncle is so far found to be hexagonal. The cone may be several 



