SUMMARY 



61 



SUMMARY 



This report presents the revised classifi- 

 cation of plants identified from their 

 isolated fossil spore coats, and deals 

 primarily with those of Paleozoic age. 

 Orthodox taxonomic procedure has been 

 followed as closely as possible for reasons 

 which are presented in the introduction. 

 A cautious policy has been followed with 

 regard to synonymy, and, even though 

 forms are very closely allied, names based 

 on different holotypes have been allowed 

 to stand. In many instances, however, 

 the apparent close relationship, which may 

 later prove conspecific, has been noted. 

 Thus names noted as synonyms are nearly 

 all objective synonyms because they are 

 based on a common holotype. Many 

 difficult problems concerning nomencla- 

 ture of fossil plants are solvable if nomen- 

 clatural types are strictly interpreted. 



About 400 named species have been in- 

 cluded in the present paper and most of 

 these have been allocated among 23 genera 

 which seem to serve a useful and signifi- 

 cant purpose in classification. Additional 

 genera no doubt will require recognition 

 later and new information will modify 

 the views that have been expressed for the 

 genera described here. A number of 

 species described previously apparently 

 do not conform sufficiently to merit in- 

 clusion in the same genus with the type 

 species of the group, and at the same time 

 do not show convincing evidence of affinity 

 with other recognized groups. Such forms 

 have been listed as species excludende. 

 Attention is directed to the several species 

 excluded from Reticulati-sporites which 

 here is interpreted in a considerably re- 

 stricted sense. Many of these forms re- 

 quire much more careful study in order to 

 arrive at a satisfactory expression of their 

 affinity and classification. Other forms 

 listed under incertae sedis also are lacking 

 in sufficiently understood biological char- 

 acteristics to support a definite systematic 

 allocation. In dealing with plant micro- 



fossils it seems unavoidable that many 

 forms worthy of description will never- 

 theless have such problematic relationship 

 that their assignment under incertae sedis 

 is obligatory. The usefulness of fossils 

 nevertheless bears a considerable relation- 

 ship to the basic and fundamental in- 

 formation available about them and for 

 this reason greatest significance must be 

 attached to species whose relationship 

 has been reliably established. 



The authors of this paper and their 

 associates have observed many new types 

 of plant microfossils in preparations from 

 coal and carbonaceous sediments in 

 America. The present synopsis is the out- 

 growth of a need for a more compre- 

 hensive survey of previous work con- 

 sidered from the standpoint of a con- 

 sistent systematic poHcy. The essential 

 features of an appropriate policy have 

 been embodied here to serve as a working 

 basis for the great amount of descriptive 

 work yet to be done. We believe that this 

 working basis will require further re- 

 vision as new information is accumulated 

 and presented. We further believe that 

 such revision can be carried out with 

 greatest efficiency and benefit to all con- 

 cerned if the orthodox usages character- 

 istic of mature systematic science are 

 adopted and critically applied. 



ACKNOWLEDGMENTS 



The authors are under particular obliga- 

 tion to Dr. W. H. Camp of the New York 

 Botanical Garden who, at a period when 

 other duties were particularly urgent and 

 pressing, nevertheless found time to read 

 the manuscript and suggest numerous 

 desirable revisions in the manner of pres- 

 entation. 



Mr. R. M. Kosanke of the Illinois 

 Survey, Dr. Gilbert H. Cady, and mem- 

 bers of the Survey editorial staff all have 

 contributed in final preparation of this 

 paper for publication. To all of these the 

 authors owe a special debt of thanks. 



