576 Reviews — W. Carruthers on the Fossil Cycadece. 



respoadence between the recent and the fossil stems, both belonging, 

 as there can be no doubt, to the same order of plants, may fairly be 

 inferred to have been produced by the same cause ; iiiat the large scars 

 are the ibases of true leaves ; the smaller scars immediately -suoceed- 

 ing them, -as is established by their slight imbrication and the «mall 

 cicatrix .<m their upper margin, supported lanceolate ^ales.; and the 

 somewhat larger si?;ed scars on the upper portion of the .constriction 

 were produced by the bases of the fruit-bearing leaves." (p. (684.) 



The genus Watesia seems to be distinguished from BucMandia by 

 having no band of specialized ,fruit-bearing leaves borne on the main 

 stem,; and the leaf- scars are nearly equal in size throughout. 



The >new genus WilUamsonia is probably among the most remark- 

 able -of the organissas herein described, and has been the -subject -of 

 mudh ccurious and interesting speculation, from the time of Young 

 and Bird (who compared the male infloresceuce to that, of the art"i- 

 ohoke) to that of Mr. Yates and Prof. Williamson (in the Proceed. 

 York. Phil. Soc.). The lat-ter gentleman, who has had these fossils 

 under his notice for thirty years, liberally offered ;to place his notes 

 at Mr. Carruthers' disposal for this memoir, but he has been persuaded 

 by the author to incorporate the numerous facts he had collected, and 

 his ingenious inteiipretation of them, in a separate memoir under the 

 title of ;^am«a gig as. From the peculiarities of the .organs of fructi- 

 fication and other characters (for the elaborate exposition of whioh 

 the reader is referred to Prof. Williamson's memoir), the genus 

 Williamsoma has been established by Mr. Carruthers. 



An elaborate and .carefully prepared diagnosis introduces the 

 genus Bennettites (Carruthers), named after his distinguished col- 

 league, and based upon some well-preserved specimens obtained 

 from the Wealden and Lower Greensand of the Isle of Wight, frag- 

 ments of which had formerly been referred to BucMandia anomala, by 

 Mantell ; it had also attracted the attention of the late Eobert Brown, 

 who observed that all the Isle of Wight Cycads agreed "in having 

 an elliptical outline, unaccompanied by any inequality in the woody 

 ellipsis, and also in having a bud in the axilla of each leaf," thus 

 differing from all other Cycad stems which are circular in outline 

 and have only scattered buds (p. 695). But the more complete ex- 

 amination of newer materials at his disposal have revealed structures 

 in the organs of fructification, as well as in the stem, which justify 

 their being placed, not only in a distinct genus, but as forming a 

 weU-marked group : one peculiarity being that the fruit is borne in 

 a secondary axis not protruding beyond the basis of the petioles. 

 Mr. Carruthers says (p. 6,98) : — 



" In comparing the structure of this plant with the inflorescence 

 of the recent Cycadece, the points of difference are more obvious than 

 those in which they agree. The most important correspondence is 

 to be found in the structure of the seed, and its envelopes. The 

 fossil is truly gymno&permous, the pollen having access to the 

 embryo-sac through the tubular openings in the covering of the seed, 

 and not through a style developed from an investing carpellary 

 organ. The most remarkable difference is to be found in the com- 



