4t>4 (1. Ji. W'wland — Williamson /'<t» Tri!><: 



of the significance and possible extent of these and related floral 

 forms, it is worth while to call attention to the view given in 

 American Fossil Cycads, p. 244, that, — 



* -x- * « yy e are cer tfvinly permitted to conjecture the 

 former existence of members of a Cycadeoidean alliance in 

 which the microsporophylls did not assume a cyclic arrange- 

 ment, and others with perchance freely branching, less com- 

 pacted trunk types, in which there was an early reduction of 

 these spirally arranged microsporophylls to a filamentous stam- 

 inate form, with, as may often happen, a certain coordination 

 between decrease in bulk and increase in number." 



And certainly with the subsequent determination of the re- 

 duced Wielandiella sporophylls and other discoveries of reduced 

 flowers, both on the Yorkshire coast and in the newly found 

 Mexican localities, the correctness of the above view is proven. 

 Only in the one detail of spiral or short-whorl arrangement of 

 the stamens is evidence slow to appear ; but such insertion 

 appears to characterize the flower shown in fig. 17 D, and in 

 any event smaller flowers with this feature must have been 

 numerous. Indeed, the general accuracy of the hypothesis of 

 a great and varied Willi am sonia group extending its relation- 

 ships far beyond the observed limits of the associated foliage 

 and fruits of the Mesozoic, as gradually developed from the 

 wider study of these fossil forms during the past dozen years, is 

 abundantly testified to and proven by a long list of field and 



laboratory results. 



* ' * * * * * * 



In the foregoing pages we have brought into view the main 

 facts known of the Williamsoniae side by side with those hypo- 

 thetical views and questions which lend a more vivid interest 

 to the investigation of an extinct group. Naturally the indi- 

 vidual worker finds his chief labor in enlarging his store of 

 accurately known material, and so it arises that as the study of 

 first one group and then another is normally extended to mate- 

 rial limits, undue significance may inadvertently be given lesser 

 facts of structure or occurrence. But although vigorous field 

 work in the case of the cycads, connoting with accuracy the 

 association of the Mesozoic cycad stems, leaves, and fruits of 

 the localities of the globe, has barely begun, the value assigned 

 their study can scarcely be overestimated. 



And just as we have seen that Cycadeoidea was the key to 

 Williamsonia, so the study of the showy flowers of the latter 

 genus has schooled us in the collection and laboratory study 

 of less conspicuous casts and imprints often exhibiting most 

 unexpected structural detail, and thus finally made us aware of 

 an immense new category of evidence of Mesozoic gymnosperm 

 development unquestionably connected with angios perm origins. 

 In fact if there is a post-Paleozoic family of fossil plants which 

 may be fairly said to now hold wider interest to students than 



