IOWA PTERIDOPHYTA. 145 



the rule that the loess-fauna of any region is essentially the 

 same as its recent terrestrial molluscan fauna, are species 

 of land-shells now living in the western, comparatively dry 

 highlands. They are Pupa muscorum (L-), Pupa blandi 

 (Morse) Binn., Spliy radium edentulum alticola (Inger.) 

 Pils, Pyramidula strigosa iowensis Pils. (represented only 

 by other varieties of the species) , and now Pyramidula 

 shimckii (Pils.) Sh. 



IOWA PTERIDOPHYTA 



in the Herbarium of the State University of Iowa. 



BY B. SHIMEK. 



It is the purpose of this paper to record the Pteridophyta 

 from Iowa now found in the herbarium of the State 

 University of Iowa. Such lists are of two-fold interest: 

 they assist the student of geographical distribution of 

 plants, and they locate material for study and reference. 



In a modest paper such as this it seems presumptuous to 

 discuss the question of nomenclature. Yet this question is 

 met in the very effort to make such a record as that here 

 presented. 



Few groups of equal size with the Pteridophyta present 

 as much variation in characters. Representing the most 

 ancient vascular vegetation which formerly formed the forests 

 of the earth, and still constituting an important feature of 

 the tropics, this subkingdom has been sufficiently plastic to 

 adjust itself to the varied conditions of several geological 

 ages, and this probably accounts for that intergradation of 

 characters which is the delight of the evolutionist, but 

 which has furnished many pitfalls to the systematise This 

 is equally true of both the more important structural and 

 developmental characters which mark larger groups, and 



