398 Professor Buckland on the Cycadeoidea, a Family of Fossil Plants 



paring it with that at the summit of the Cycas revoluta which bore fruit at 

 Farnham in 1799, of which a description and plate are given by Sir J. Smith*. 

 This cavity is surrounded with a magnificent crown of leaves, whose stalks are 

 set round its margin like the bases of the leaves in our fossil specimen f. The 

 cavity itself is occupied by a cluster of fronds producing the fruit or drupae ; 

 and it is a striking coincidence, that Sir J. Smith, in describing this cavity, 

 makes use of the same comparison (hollow like a bird's nest) which has been 

 applied by the quarry-men at Portland to the fossils I am now associating 

 with the recent Cycadeas. In the central cavity of this fossil there are no 

 remains of fronds or fruit, but a convex mass of cellular tissue, which probably 

 formed the support of the proliferous fronds. Where the trunk is broken 

 below the summit;};, we find the same central mass of cellular tissue as in the 

 transverse section of the stems of recent Zamiae and Cycades. 



Near the circumference of both specimens there is a laminated circle as in 

 the trunk of a recent Zamia, but differing in that it is much broader and 

 placed nearer the circumference of the stem : the large and visible plates of 

 this circle, when magnified with a lens§, appear made up of smaller plates 

 almost invisible to the naked eye, more numerous and closer to each other 

 than in the laminated circles of recent Zamia. 



Between this radiating circle and the outer case of leaf-stalks, is a narrow 

 band, or ring, of minutely cellular substance, analogous to the similar but 

 much broader band of cellular tissue that divides the radiating circles from 

 the bases of the leaves in the recent Cycadeae ||. 



In the second and smaller species {Cycadeoidea microphylla) the bases of 

 the leaves are also lozenge-shaped and about an inch in length, but small and 

 numerous, much like those of the Xanthorrhcea or gum-plant of New South 

 Wales. The trunk is longer in proportion to its width, whilst its transverse 

 section exhibits at the centre the same indistinctly cellular appearance as the 

 species last described ; but near the circumference instead of one it has two 

 laminated circles, and exterior to each of these a narrow band devoid of 

 lamina;, analogous to the two bands of cellular substance that are placed in 

 similar relation to the two laminated circles in a recent Cycas IT. 



These two circles, like the one circle of Cycadeoidea megalophylla, ap- 

 proach the circumference, whilst those in Zamia and Cycas are placed nearer 

 the cenlrc of the stem. 



* Transactions of the Linnean Society, Plate 29. p. 312. 



t riate XLVII. fig. 1. + See Plate XLVIII. § Plate XLVIII. fig. 2. & 3. 



II See Plate XLVII. fig. 1. Plate XLVIII. fig. 1. & 3. Plate XLVI. fig. 1. & 3. 



f See Plate XLIX. fig. 1. & 2; and PI. XLVI. fig. 1. 



