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 mol- 
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 from Diedrocephala. 
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 
