Epiaeschna heros and Æschna verticalis and constricta may occasionally be seen, especially about the time the sun sets, catching small insects for food. Anax junius is the most conspicuous species in the locality from May to September.
Macromia illinoiensis is a very common species. At certain times the males and females of this species may be found in numbers in quiet places among bushes, where they come to rest on the under side of branches, their bodies being at an angle of about thirty degrees with the branch. They are easily approached at such times, and two females and four males have been taken at a single sweep of the net.
Epicordulia princeps, Tetragoneuria cynosura, Tramea carolina and lacerata and Pantala flavescens are occasionally seen.
Neurocordulia yamaskanensis has only been taken once on Rattlesnake Island. It is a rare species, but one that is more common in the northern states.
The genus Libellula is represented by basalis, 4-maculata, semifasciata, pulchella and incesta; and Sympetrum by obtrusum, rubicundulum, vicinum, senicinctum and corruptum.
Pachydiplax longipennis, Plathemis lydia, mesothemis simplicicollis, Perithemis domitia, Leucorhinia intacta and Celethemis eponina and elisa are abundant, and with the members of the genus Libellula furnish a very large percentage of the dragonfly life of the Sandusky Marshes.
SPONGES AND BRYOZOANS OF SANDUSKY BAY.
F. L. Landacre.
The two small groups of fresh water sponges and Bryozoa received some attention at the Lake laboratory during the summer of 1900.
All our fresh water sponges belong to one family, the Spongillidae, which has about seven genera. They differ from the marine sponges in two particulars. They form skeletons of silicon only, while marine sponges may form silicious or limy or spongin skeletons. The spongin skeleton is the one that gives the bath sponge its value.