36 IOWA ACADEMY OF SCIENCES. 



tributed to the confusion. There is much in synonomy 

 yet to be worked out which can only be completed when 

 the species of the different countries have been carefully 

 collected and accurately determined as to specific and 

 varietal limits. 



The bibliography of our forms in this group has been so 

 carefully and accurately worked out by Van Duzee in his 

 Catalogue of the Jassoidea that it seemed unnecessary to 

 repeat it here. Under each species is given the reference 

 to the original description and the date, and reference to 

 the descriptions of all synonyms and varieties. In addi- 

 tion to this, references are given to systematic works pub- 

 lished since the Van Duzee Catalogue, and references that 

 have been changed from that given in the catalogue, are 

 included, when necessary to make them clear. 



There are few characters that seem available for generic 

 use, and consequently, the classification within certain 

 parts of the group is very unsatisfactory. With a limited 

 number of species, such as we possess, one may readily lay 

 down characters that will separate them into well-defined 

 genera, but with a large number the task becomes more 

 difficult. 



The author has followed Stal in generic disposition, the 

 main objection to this system being that the genus Tetti- 

 gonia is still burdened with an immense number of quite 

 diverse species. Even in our fauna it contains quite 

 widely separated forms. It will, however, be necessary 

 to study carefully a representative series from tropical 

 regions before any rational and permanent separation can 

 be had. On the other hand, the group represented by niol- 

 lipes is mainly temperate in distribution, we having seven 

 species in our fauna, of which Fowler only records two for 

 Mexico and Central America, and it has been thought best 

 to separate it froviPDiedrocephala. 



The adoption of a system of describing by means of vari- 

 eties, in some cases, was but the choice of evils, it seeming 

 to be almost impossible to define some of the variable 

 forms in any other way. Having adopted that method, it 

 seems preferable to designate them by names rather than 



