Vol. 59.] OCCURRENCE OF DICTYOZAMITES IN ENGLAND. 221 



division, the Cycadales. We may, therefore, as Prof. Nathorst has 

 suggested, employ the term Cycadophyta as a group-name for 

 Cycadean plants, comprising the two subdivisions Cycadales and 

 Bennettitales, the distinguishing characters of which are furnished 

 by the reproductive structures. In dealing with the numerous fossil 

 leaves which are in all probability Cycadean, but cannot, through 

 lack of evidence, be referred to one or other of the two subdivisions, 

 we can best express our opinion as to their probable taxonomic 

 position, and at the same time oar ignorance as to their precise 

 affinity, by speaking of them as members of the Cycadophyta. 



CYCADOPHYTA, Nathorst. 

 [Kongl. Svensk. Yetenskaps-Akad. Handl. vol. xxxvi, no. 4, p. 3.] 



Genus Dictyozamites, Oldham. 

 [Mem. Geol. Surv. India, Pal. Indica, ser. 2, vol. i, p. 40.] 



Pronds pinnate, similar in habit to those of Otozamites ; pinnae 

 sessile, or with a very short stalk, disposed in two alternate rows, 

 and attached to the rachis either by the middle or by the lower 

 half of the base. The basal free portion of the pinnae is usually 

 slightly auriculate. The central portion of the lamina of the pinnae 

 is occupied by veins which follow a longitudinal and approximately- 

 parallel course, and are connected one with tbe other by oblique 

 anastomoses ; the veins of the median region give off branches 

 which curve obliquely upward and downward to the margin of 

 the leaflet, and by repeated cross-connections with one another 

 divide the lamina into numerous polygonal meshes or reticula. 



Stems and flowers unknown. 



Dictyozamites Hawelli, sp. nov. (PI XY, figs. 1-4.) 

 Fronds pinnate ; pinnae crowded, sessile, in two alternating rows, 

 attached by a small portion of the lamina slightly below the 

 middle of the base to the upper face of the rachis. The pinnae are 

 broadly linear in shape, and taper gradually to a bluntly rounded 

 apex ; the upper margin of the base is slightly auriculate, the lower 

 margin rounded or very slightly auriculate. 



Yeins numerous ; those in the median region are approximately 

 parallel to the edges of the pinna, and from them branches are 

 given off which pass obliquely upw T ard and downward towards 

 the margin of the lamina. 



The material from Marske consists of small and imperfect pieces 

 of fronds, but is sufficient to form the type of a distinct species, 

 distinguished from Dictyozamites faleatus (Morr.) by the relatively 

 greater breadth of the segments, their more linear instead of a 

 falcate form, and by the attachment to the rachis being slightly 

 below the middle of the pinna-base. Prom the Japanese type 

 D. Hawelli differs in the more crowded arrangement of the segments 

 and in their blunter apices 



