OF LOWER QBEEVSAXD PLANTS. 299 



organs of reproduction ; 2nd, one of these cones " (Cycadeostrobus 

 Wdlkeri, Carr.) has been found in the same stratum in which 

 the stem of Yatesia Morrisii is found." It is now realised how 

 weak is the evidence based on chance association of rare speci- 

 mens, and in the actual specimens of C. Yatesii there is no sign 

 of any fructification, nor are there any features in the stem or 

 leaf-bases which could serve as a justifiable basis for theoretical 

 re-constructions of its fruits. 



Cycadeoidea Yatesii, Carruthers. 

 [Text-figs. 93-97.] 



1867. Cycadeoidea Yatesii, Cavruthers, Geol. Mag., vol. 4, pp. 199- 



201, pi. ix, figs. 1 &2. 

 1870. Yatesia Morrisii. Camithers, Trans. Linn. Soc. Lond., vol. 26, 



p. 688, pi. Iv, figs. 3-6 ; pi. Ix, fig. 13. 



1874. Yatesia Morrmi, Schimper, Trait. Paleont. Ve"g., vol. 3, p. 555. 

 1895. Yatesia Morrmi, Seward, Cat. Mesoz. Plants, Wealden Mora, 



vol. 2, pp. 166-7. 



Diagnosis. Species is founded on vegetative trunks showing 

 pith, wood, and leaf-bases ; the inner tissues petrified to show 

 imperfectly preserved anatomical details. Trunk cylindrical, 

 relatively slender for its height, measuring not less than 25 cm. 

 long and 12 cm. in diameter, the axis in this length being quite 

 straight, without any sign of termination or reduction, and 

 having every appearance of having been much longer. Petiole- 

 bases closely arranged in compact regular spirals completely 

 covering the stem. Petiole-bases mostly very regular and 

 uniform in size, measuring l'8-2 cm. in transverse and 1'6- 

 2 cm. in vertical direction ; some few are less and others more 

 than this. Where it is not worn down, the petiole-base 

 terminates in a rounded tumid boss, directed upwards. Between 

 the petiole-bases the ramental (?) zones are narrow. The pith is 

 very large, as much as 8 cm. in diameter in a stem only 12 cm. 

 in diameter including the outermost leaf-bases. Surface-cast 

 of pith shows deep grooves and ridges, with lenticular ridges 

 due to the broad rays between vascular strands. Two slender 

 wood-cylinders surround the pith, each about 5-8 mm. thick, 

 and composed of radiating zones of secondary wood and between 

 them a zone about 2*5 mm. thick of different tissues (phloem ?). 

 Trucheids in close regular series, averaging up to 30-40 JL* in 



