SCUTELLEROIDEA OF IOWA 7 
of tropical and subtropical regions. It is the largest group of the 
Heteroptera and approximately 6,000 recent species have been 
described while about 150 fossil forms have been discovered. 
Most of the latter are from the Tertiaries of Europe and America. 
But 235 modern species are recorded from America north 
of Mexico by Van Duzee’; they are distributed in the three 
families as follows: 
Seutelleridae—l4 genera—26 species 
Cydnidae—10 genera—45 species 
Pentatomidae—54 genera—164 species 
Of Iowa forms, the total recorded number for the state is, with 
this paper, brought to 65 species and subspecies distributed in 
the three families as follows: 
Scutelleridae—2 genera—4 species 
Cydnidae—6 genera—12 species 
Pentatomidae—25 genera—47 species and subspecies. 
Comparatively few of the American genera are represented 
in Europe and the center of dispersal in both Palaeartie and 
Nearctiec regions seems to have been in the south. The genus 
Nezara enjoys an exceptionally wide distribution being univer- 
sally distributed in Nearctic, Neotropical, Palaearctic, Ethiopian, 
Oriental and Australian regions. 
The pentatomid records at hand seem to show that the 
encroachment of heretofore unrecorded forms is from the west 
and southwest and that the wave of dispersal is towards the 
north and northeast. In substantiation of this statement the 
following recent additions to our fauna may be mentioned; 
Cydnus obliquus Uhler, Prionosoma podopioides Uhler, Mur- 
gantia histrionicca Hahn and Euschistus tristigmus var. 
pyrrhocerus H. 8. | 
The state of Iowa is situated near the center of the United 
States lying between 40° 20’ and 45° 30’ north latitude and be- 
tween 90° 15’ and 96° 43’ west longitude. The greatest 
length from east to west is about 328 miles and the greatest width 
from north to south is about 215 miles. The area is roughly 
55,480 square miles most of which is a more or less ‘‘monotonous 

1Van Duzee, E. P., Check List of the Hemiptera of America North of Mexico, 
N. Y. Ent. Soc., 1916. . 
