The nemertinea are a progressive race. Some have invaded the deep sea and some the dry land. They have been obtained from depths of more than 6,000 feet. The deep-sea species have undergone peculiar adaptations for a life of swimming slowly or floating idly at whatever depths they have chosen for their habitat. They have lost their eyes and their brains are quite rudimentary compared with those of their land or shallow-water relatives. All have increased greatly the amount of gelatinous tissue between the internal organs, so that they have a low specific gravity. The deep-sea forms thus far collected are broad and flat. Some have taken on the appearance of small fish with outgrowths on the sides of the body which resemble fins, and with the rear end flattened like a fish’s tail. Some have developed tentacles around their mouths. Most of the ribbon worms of the open sea are nearly transparent. Some, however, are among the most brilliantly colored of the nemertinea race, with coat patterns of yellow, orange, red, and scarlet. Most of these creatures are small, measuring only a fraction of an inch in length. The largest is about six inches long—thus, as one biologist points out, comparing to the smallest like an ox to a mouse. These pelagic species are found in all the oceans. They are carried around the world by deep-sea currents. About twelve species have abandoned the shore for dry land where they lead active lives and seem to have become almost independent of water. They cannot, however, endure being completely dried out. They do not make their own burrows, but in periods of drought, it is believed, they make use of earthworm burrows. Some have been found under the dead, damp bark of tropical trees. Their chief food consists of earthworms. _Winged Reptile_ The largest flying animal the world has known was a winged reptile, the pterodactyl, of a hundred million years ago. It had a wing spread of more than twenty feet, supporting in the air a body which would hardly have weighed more than thirty pounds. Its head was nearly four feet long with a dagger-like, narrow, pointed toothless beak. It lived around the ancient sea which once extended northwestward from the present Gulf of Mexico through most of Kansas. Presumably it lived entirely on fish and made long, gliding flights over the water. The structure of this reptile, insofar as it could be realized from fragmentary fossil bones, was studied carefully by Dr. Samuel P. Langley while he was at work on early models of his airplane. Did the pterodactyl, Dr. Langley asked in a somewhat pessimistic progress report, represent the best Nature could do in the way of flight? Could man hope to do better than Nature? _Vicious Fire Ants_