OF LOWEft GRKESSAKD PLANTS. 305 



between adjacent leaf-bases; where they are broken away, the 

 narrow lateral extension of the leaf-base can be seen. 



AFFINITIES. In his description of this specimen Carruthers 

 (1867 A) merely said "it must be referred to Buckland's genus 

 Cycadeoidea = Mantellia Brongn." Carruthers notes that " the 

 woody cylinder surrounding the pith consists of two rings, 

 everywhere pierced by medullary rays, which are often so large 

 as to separate the rings into numerous series of woody wedges, 

 as in recent Cycadeae." Regarding the rather unusual form of 

 the leaf-bases he notes : " Our species may be distinguished from, 

 the others [of the Cycadeoidea] by the regular arrangement and 

 symmetrical form of the bases of the petioles. They are rhom- 

 boids, the horizontal diameter of which is but little more than 

 the perpendicular, and differing in this respect not only from 

 all the other described recent \_sic. fossil ?] species, but also 

 from all the living Cycads with which I am acquainted." 



This accurate description, and the recognition that the plant 

 had affinities with Buckland's Cycadeoidea, was confused by 

 Carruthers himself (1870) when he founded the genus Yatesia 

 in which he placed this fossil, re-naming it Yatesia Morrisii. 

 The genus Yatesia was diagnosed as follows: "Trunk 

 cylindrical, of uniform thickness, and covered with the short 

 persistent bases of the petioles ; scars of the aborted leaves 

 scattered among those of the true leaves. Andrcecium un- 

 known ; gyncecium forming a cone, each carpophyll of which 

 bears two reflexed ovules." 



There is no evidence that the present specimen had any of 

 these characters, beyond the cylindrical trunk and persistent 

 leaf-bases. The deductions regarding its fructifications are 

 assumptions ; while it is not impossible that they may prove 

 correct, as there is no actual evidence to support them, they 

 cannot be used as the foundations of a genus. Whether or not 

 the genus Yatesia may hold for other species cannot be discussed 

 here : it is certain, that as diagnosed, the plant now under 

 consideration cannot be included in the genus Yatesia. 



V. 13238. Type-specimen. Figured, Carruthers, Geol. Mag., 

 vol. 4, 1867, pi. ix, figs. 1 & 2. Carruthers, Trans. 

 Linn. Soc., vol. 26, 1870, pi. Iv, figs. 3-6; pi. Ix, 

 fig. 13. Text-figs. 93, 95. This type-specimen is 



x 



