136 Morphology BOOK i 



tion of Zygopteris, and grouped the two genera together 

 in one family, so founding the Botryopterideae, a group 

 of primitive ferns, to which he assigned a position between 

 the existing Filices and the Ophioglossaceae. This was, 

 perhaps, the most important of his early work. About the 

 same time, or a little earlier, he made contributions to the 

 knowledge of the group known a little later as the Cycado- 

 filices, showing that the fronds of Neuropteris and Ale- 

 thopteris were borne on petioles of the type of Brongniart's 

 Myeloxylon. These were some years later found to be 

 the petioles of Cotta's Medullosa stems, and were included 

 in the Cycadofilices towards the close of the century. 

 Renault, at the time, held them to be ferns showing affinities 

 with the Marattiaceae. 



The next important work calling for mention was his 

 wonderful account of the minute structure of the Cordaiteae, 

 which he undertook in collaboration with Grand'Eury, in 

 1879. The details of the work are given in the memoir 

 Sur la structure comparee de quelques tiges de la Flore 

 Carbonifere. 



Renault was fortunate in his collaborators. Not only 

 did he work with Grand 'Eury, in the researches already 

 mentioned, but he had in turn the help of Zeiller and of 

 Bertrand. In 1889 he published with the assistance of 

 the former, a complete account of a rich flora of Upper 

 Coal-measure age, under the title Etude sur le terrain 

 houiller de Commentry, which was followed a few years 

 later by his last great work, Flore fossile du bassin houiller 

 et permien d'Autun et d'pinac. His own contribution to 

 this was the second volume, published 1893-6 ; it contained 

 descriptions of the internal structure of all groups of the 

 palaeozoic plants. The first volume, which dealt with the 

 Ferns, was written by Zeiller and published in 1890. 



With Bertrand he investigated the structure of the 

 Poroxyleae, a group he had discovered in 1879. The 



