1526 CORMOPHYTA. 



bipinnate, are simply pinnate ; their structure is very firm, and they 

 usually develop in a circinate manner like ferns. The plants are 

 male and female ; the male fructification being borne in cones (fig. 

 1394), while in the female the ovules are usually situated on the 

 margin of modified leaves or on the base of scales. 



Existing Cycads are divided into the families Cycadece, Encepha- 

 lartece, Stangeriece, and Zamiece. Of these the living South African 

 genus Encephalartos occurs in the Miocene of Eubcea, and perhaps 

 in the Rhaetic of Honduras ; while a leaf from the Miocene of Styria 

 has been referred to the Mexican genus Ceratoza??iia, belonging to 

 the Zamiece. 



The family position of extinct genera is for the most part un- 

 certain, and it is accordingly unadvisable to make any attempt at 

 such divisions. As is usually the case with fossil plants, genera 

 have been founded upon different portions of the organism, so that 

 in many cases we doubtless have the same type described under 

 two or more names. In the Mesozoic, as Sir J. W. Dawson remarks, 

 Cycads had a world-wide distribution, and many of the undermen- 

 tioned European genera likewise occur in America. The species 

 occurring in the Cretaceous of Greenland are, according to the same 

 authority, of small size and low growth, so that they may have been 

 protected from the winter snows. Some of the more southern forms 

 attained, however, a considerable height, and must have resembled 

 palms. The order is known from the Carboniferous upwards. 



Genera founded on Leaves. — The genera based on the 

 evidence of leaves will be taken first. Of these Cycadites has the 

 leaflets attached by the whole width of their base to the stem, with 

 a single vein, while the young leaves are circinate ; in all of which 

 respects it approximates to the existing Cycas. It occurs in Europe 

 from the Carboniferous to the Upper Cretaceous ; and in India it 

 is characteristic of the Upper Gondwanas. Podozamites with small 

 leaves, and the leaflets alternating and narrowed at the base, ranges 

 in Europe from the Rhaetic throughout the Jurassic and into the 

 Lower Cretaceous ; it is also found in the Dakota Cretaceous, in 

 the Upper Gondwanas of India, and in the reputed Trias of New 

 Zealand. Till something is known of its fructification the affinities 

 of this genus cannot be determined. Zamites, again, is a very large 

 genus with small or medium-sized leaves, in which the leaflets are 

 attached by a calus to the upper surface of the stem, and are subject 

 to a considerable variation of form. In Europe this genus is well 

 represented from the Middle Trias to the Upper Cretaceous .(Green- 

 land), an isolated species being found in the Miocene. It is also 

 recorded from the reputed Trias of New Zealand, and the Upper 

 Gondwanas of India. Glossozamites includes large-leaved Cycads 

 with subsymmetrical leaflets, occurring typically in the European 



