MEDULLOSEAE 461 



definite genera and species of frond. Considering the 

 wide field covered by M. Grand'Eury's observations, 

 and the fact, which he established, of the social growth 

 of plants of the same group, there can be no doubt of 

 the value of the conclusions arrived at. M. Grand'Eury 

 is led to refer some fifteen genera or sub-genera of 

 seeds to the Neuropterideae, the general characters of 

 the seeds being that they are of radial symmetry, and 

 striated, polygonal, or winged, the number of the angles 

 or wings being some multiple of three. 



Among Grand'Eury's special results we may mention 

 that he refers the huge seed Pachytesta gigantea (some- 

 times 4 inches long) to a species of Alethopteris (A. 

 Grandint) and smaller seeds of the same type to other 

 species of the genus. In the Northern Coal-fields, 

 however, he finds Trigonocarpus seeds associated with 

 certain Alethopterids (in agreement with our conclusion 

 as to T. Parkinsoni), and points out the affinity between 

 Pachytesta and Trigonocarpus. 



A considerable variety of seeds is referred to Neuro- 

 pteris ; the seed attributed to N. flexuosa appears to be 

 of the same type as that of N. heterophylla, discovered 

 by Kidston. 



Various seeds are also referred (not to mention 

 other cases) to the genera Odontopteris and Linopteris 

 ( = Dictyopteris), which are some of those which Stur 

 had already removed from the Ferns in 1883. 



M. Grand'Eury has in several cases detected the 

 " inflorescence " or fertile rachis on which the seeds 

 were borne, but details have not yet been published. 

 He is of the opinion that, as a rule, the organs of 

 reproduction of Neuropterideae and other Pteridosperms 



