EXPLANATION OF THE PLATES. 



substance containing sago, in which seven laminated circles are disposed near the 

 centre, with a broad ring of cellular matter exterior to the outer circle. Accord- 

 ing to this drawing, the case of the trunk has smooth rings, and is not so entirely 

 composed of the bases of leaves and stipules as in the recent specimen of Cycas 

 circinalis, engraved by Dr. Hooker, PI. 2826 of Curtis's Bot. Mag. July, 1828 : 

 and as there can be no doubt of the accuracy of this plate, it is probable that in 

 the older drawing of Rheede, this part of the structure was incorrectly represent- 

 ed. Dr. Hooker observes that in Richard's plate, as in that of Rheede, the stems 

 are strongly annulated, more so than Dr. Hamilton ever saw them on the growing 

 plant. For further details connected with this subject, see Richard's Memoires 

 sur les Coniferes et Ci/cadees ; Mr. R, Brown's Appendix to Capt. King's Narra- 

 tive of a Survey of the Coast of Australia; and Curtis's Bot. Mag. No. 18 and 

 19, New Series, June and July, 1828. 



Fig. 3, represents a section of a Zamia horrida, in the possession of Charles Stokes, 

 Esq. made in the direction of the line A B fig. 4. 



Fig. 4. Reduced representation of a living plant of Zamia horrida. 



Plate XLVII. 



Cj/cadeoidea megalophylla. — The peculiar features of this specimen have been so fully 

 explained in the text, as to render further description needless. 



Plate XLVIII. 



Cycadeoidea megalophylla. — This specimen supplies the structure of important parts of 

 the fossil Caudex, which are scarcely visible to the naked eye. The magnified 

 appearance represented at fig. 2, is distinctly to be seen with a small lens on the 

 parts of the laminated circle ABC, which are converted into chalcedony : where 

 the stone is more coarse, the internal structure is less apparent. 



Fig. 3, is taken from the bottom of the specimen, and shows the junction of the lami- 

 nated circle with the external cellular ring and central cellular substance. 



Plate XLIX. 



This is the only specimen of Cycadeoidea microphylla which the author has seen. 

 The transverse section is below the summit of the stem, and consequently displays 

 no central cavity : the border of leaf-stalks surrounding the stem is much more 

 narrow than in Cycadeoidea megalophylla, and the form and proportions of the 

 plant are very diflTerent. 



