150 Morphology BOOK i 



combine the characters of Cycadaceae, Coniferae, and Gink- 

 goaceae. In 1879 Renault discovered the group Poroxyleae, 

 and with the collaboration of Bertrand published a full 

 account of their structure. They showed that the group 

 was intermediate between the Cordaiteae and lower forms. 



In 1881 Heer showed that Ginkgo is the surviving 

 representative of a series of allied plants, which are very 

 abundant in the Rhaetic beds. 



The mesozoic type Bennettites attracted a good deal of 

 notice during the period we are reviewing. It was originally 

 discovered by Carruthers in 1868, and he founded the genus 

 for certain Cycadean stems occurring in the oolitic and 

 lower cretaceous formations. He described the structure 

 of the stem and gave a very full account of the fructifica- 

 tion, or rather what he took to be the female flower. 

 Nothing more was discovered of it for some years, indeed 

 doubt was cast upon the supposed relations between the 

 flowers and the stem. In 1880 Nathorst suggested that 

 the plant bearing the flowers was parasitic on the Bennet- 

 tites, and made a comparison between it and Lophophyllum. 

 Saporta in 1885 suggested that it was a Proangiosperm 

 and classed it with the fossil Williamsonia. 



In 1887 Solms-Laubach re-examined Carruthers's fossil and 

 discovered the dicotyledonous embryo and the exalbuminous 

 seed. He contributed a further memoir upon the plant in 

 1891, and in the next year in conjunction with Capellini 

 he published descriptions of the specimens which are in the 

 Italian museums. In 1894 Lignier described a specimen 

 obtained from the Oxfordian of Normandy. 



The true nature of the flower and the minute structure 

 of the plant were investigated at the end of the century 

 by Wieland. Though he did not publish his final results 

 till 1906, they may be briefly summarized here. The 

 flowers proved to be hermaphrodite and very highly 

 organized, possessing a protective perianth or involucre, 



