Allee (1, 2) asserts that the rheotactic reaction alone is not sufficient to account for the position isopods assume in streams, and that the thigmotaxis is also of importance. The molting period and breeding season are important in the ecology of stream isopods since they decrease the clinging ability. Other experiments show that the survival time in potassium cyanide is, for Asellus communis, inversely proportional to the rate of metabolism. Since isopods which are strongly positive to current have a much shorter survival time than those which are indifferent, it appears that high positiveness to current is an expression of a relatively high rate of metabolism. Allen's (3) investigations show that in fresh water mussels the surfaces of the gills, the end of the upper part of the mantle, and the labial palps serve to carry food to the mouth. The food supply is not regulated but the amount of digestive juices secreted, and hence of digestion accomplished, depends upon the need for food. Digestion seems to be mostly accomplished in the stomach as few living organisms were found to have entered the intestine. A discussion of the possible use of the crystalline style is given. Armbruster (4) in a very interesting paper on humble-bees describes the architecture and building materials of the nests, relation of sexes, color varieties, and orientation. He believes that bees usually find the way back to the hive by "optical signals"