5. One species is free, and feeds upon anything it meets with, even pectens and echini; it appears to have no visible excrement, and in this respect it resembles plants. There are two kinds of acalephe, some small and more eatable, others large and hard, such as are found near Chalcis. During winter their flesh is compact, wherefore in this season they are caught and eaten; in summer time they perish, for they become soft; if they are touched they soon melt down, and cannot by any means be taken away. When suffering from heat, they prefer getting under stones. I have now treated of malacia, malacostraca, testacea, and of their external and internal parts. CHAPTER VII. 1. Insects must now be treated of in the same manner. This is a class which contains many forms, and no common name has been given to unite those that are naturally related, as the bee, anthrene,[136] and wasp, and such like; again, those which have their wings enclosed in a case, as the melolontha,[137] carabus,[138] cantharis, and such like. The common parts of all insects are three--the head, the abdomen, and the third, which is between these, such as in other animals is the breast and back. In many insects this is one, but in the long insects with many legs, the middle parts are equal to the number of segments. [136] Wild bee. [137] Chafer. [138] Beetle. 2. All insects survive being divided, except those which are naturally cold, or soon become so from their small size, so that wasps live after they are cut asunder; either the head or the abdomen will live if united to the thorax, but the head will not live alone. Those which are long, and have many feet, will survive division for a considerable time; both the extremities are capable of motion, for they walk both upon the part cut off and upon the tail, as that which is called scolopendra. All of them have eyes, but no other manifest organs of sense, except that some have a tongue. All the testacea have this organ, which serves the double purpose of tasting and drawing food into the mouth. 3. In some of them this organ is soft; in others very strong, as in the purpura; in the myops and œstrus this member is strong, and in a great many more; for this member is used as a weapon by all those that have no caudal sting.