Springtails (Collembola) of the St. Louis Area al 
other as 1, 1.6, 1.8, 2.2; mucro four-toothed, dentes crenulate 
dorsally ; tenent hair absent, sparsely covered with small setae; 
unguis with 2 lateral teeth, inner margin untoothed; unguiculus 
approximately one-half to two-thirds the length of the unguis; 
eyes eight on each side. 
This species and Podura aquatica L. were found in great 
abundance on the margins of lakes and ponds. The median 
dorsal black stripe which varies somewhat in the individuals 
examined serves best as a single characteristic by which this 
form may be identified. Dr. Folsom states that this species 
is common and cosmopolitan in distribution and very important 
as food for trout an inch or less in length. Records: December 
24, 1936; one mile southwest of Warrensburg, Missouri; (E. D. 
Bueker). : 
GENUS Jsotoma Bourlet, 1839 
Manubrium much shorter than the dentes. Unguiculus and 
furcula present. The third and fourth abdominal segments about 
€qual. Eyes variable. Corpus of tenaculum usually with many 
anterior setae, 
Isotoma viridis Bourlet, 1839 
_ Figures 36-38; length 2-4 mm.; most specimens preserved 
in alcohol are a yellow green or a dark green; the body seg- 
ments banded posteriorly with darker chitin; antennae four- 
Segmented, one and one-half to two times the length of the head, 
Second and third segments subequal and 1.8 times the length of 
the first Segment, fourth segment twice the first; all segments 
_ Of the body very distinct, third segment slightly longer than the 
fourth and extending ventrally beneath the fourth; furcula at- 
tached to the fifth segment and extending to the ventral tube; 
tenaculum quadridentate ; unguis with two lateral teeth and a 
very distinct tooth on the outer edge, two small inconspicuous 
teeth on the inner edge, inner teeth sometimes absent ; unguiculus 
