740 



THE AMEBIC AX NATURALIST [Vol. XLII 



somacese, Hymenophyllacea\ most Dieksoniea\ Dennsta-dtiinae, 

 Cyatheacefe (Salviniaceas) ? The remaining families often 

 grouped together as Polypodiacea^ form the group of the Mixta?. 



The Botryopterideas comprise some of the earliest known fossil 

 Filicales. Their affinities, however, are somewhat obscure, and 

 the group seems to have been a synthetic one. They show cer- 

 tain evidences of affinity with the Marattiaeeffl also with the 

 Osmundaeea- and Ilymenophyllaeea\ It might also be suggested 

 that a comparison of the spora ngium might be made with Botry- 

 chium and perhaps Ilelminthostachys. 



We must pass over with brief mention the very detailed ac- 

 count of the ferns which occupies over 150 pages of the text. 

 The tendency in the evolution of the sporangium is very clearly 

 from the larger eusporangiate type of the Marattiacese reaching 

 its maximum in Kaulfussia, where nearly 8,000 spores occur in 

 the single sporangium, to the numerous, small leptosporangiate 

 sporangia of the Mixta- where there may be only from 8 to 64 

 spores. It may be added lhat the sporangia of Ophioglossum 

 represent a still more primitive type, both in their large size, 

 their indefinite limits and very great number of spores. 



The assumed relation of the different families of the Filicales is 



Part III is { , summary covering some sixty pages. The most 

 Ah, a suggest in their post-sexual phast how tht imitation of 



be held to be blind brand,, s of d<sr, ,,/, which illustrate neverthe- 

 less phyletic progressions that illuminate the origin of sterile 

 tissues from those potentially fertile, and the establishment of a 

 self -nourishing system in the sporophyte. " "It may accordingly 

 be concluded as probable that the prothallus of early Pterido- 

 phytes at large was a relatively massive green structure, with- 

 di i ply sank sexual organs." 



The Lycopodiales stand by themselves in the simplicity of the 

 sporangial arrangement and constitute a type of extreme an- 

 tiquity, which has come down practically unaltered to the present 

 day. Their comparative study may be conducted independently 

 of other phyla: for there is no reason to think that they were 

 derived from any other known vascular type Tin , ,,„,/,- 



