288 
Psyche 
[June-September 
Table 1 Comparison of Paleopterous Species from Elmo and Midco Beds 
ORDERS 
NUMBERS OF SPECIES 
Elmo 
Midco 
Elmo & Midco 
Palaeodictyoptera 
3 
1 
0 
Megasecoptera 
5 
5 
1 
Diaphanopterodea 
7 
14 
3 
Protodonata 
5 
3 
1 
Odonata 
4 
5 
2 ' 
Ephemeroptera 
8 
5 
1 
32 
33 
8 
apparently contemporaneous. However, there appear to have been 
differences in the environments of the lakes (Raasch, 1946). The one 
in Kansas contained fresh water, derived from an earlier swamp, 
with plants growing close to the water’s edge and with some insect 
nymphs living in the water. The Midco lake was essentially a playa, 
containing algae and Conchostraca; plants did not grow near it and 
insect nymphs did not live in it. 9 
Now that the study of the Palaeoptera in the Midco beds has been 
completed, it is of some interest to compare the numbers of species 
represented in each deposit and common to both deposits. These 
figures are given in the accompanying table (Table 1). The total 
number of species in each of the beds is very close, and the number 
of species in each order corresponds closely except for the Diapha- 
nopterodea, of which there are twice as many in the Midco beds as 
at Elmo. It appears that, on the average, about one-quarter of the 
Midco species collected also occur at Elmo. 
References Cited 
Carpenter, F. M. 
1930. The Lower Permian insects of Kansas. Part 3. The Protohymenoptera. 
Psyche 37:343-374. 
1932. The Lower Permian insects of Kansas. Part 5. Psocoptera and additions 
to the Homoptera. Amer Journ Sci 24:1-22. 
1933. The Lower Permian insects of Kansas. Part 6. Delopteridae, Protely- 
troptera, Plectoptera, and a new collection of Protodonata, Odonata, 
Megasecoptera, Homoptera, and Psocoptera. Proc Amer Acad Arts Sci 
68:411-503. 
9 The fossil mayfly nymphs discussed above were apparently the cuticular remains 
shed by the nymphs at moulting and carried down streams to the lake. 
