Most numerous of American limestone cavern animals are white, blind grasshoppers—the cave crickets. They are small insects with antennae about an inch long. With these they feel their way over the dank walls upon which they swarm. Best known are three species of cave fish, minnow-like and from two to three inches long. They have not lost their eyes entirely, although these long since have been sightless. They have compensated for the loss of sight by an extremely acute sense of touch. The slightest movement of the water will send a school of them scurrying for shelter among the rocks. The blind white worms are supposedly their chief food. None of the cave animals are very aggressive. Their chief nutriment is believed to be organic matter carried by water, which seeps into the dank chambers from the world above, but how they make use of this is unknown. All are quite primitive types which have remained very conservative after their first migration from the world of light into the world of darkness. They are old both racially and in their behavior as individuals. Secure in the black depths, some of them are quite likely to be the last living creatures on earth. _The Remarkable Clam Worms_ Fantastic giant of the nemertinean race is Cerebratulus lactus, commonly known as “the clam worm” along the Atlantic Coast from Florida to Massachusetts. It is from ten to twelve feet long, can contract to two feet, and is an inch wide. Its favorite dwelling is a burrow six to eight inches below the surface, usually in an old mussel bed among broken shells and stones where it is almost impossible to sink a clam hoe. Outside the burrows it is seldom seen except occasionally at high tide, gliding among sea weeds or in the shade of rocks in tidal pools. It is unlikely that any burrow is occupied very long, as the nemertinea is moving about constantly through mud in search of food. The animal is highly specialized for burrowing. Ordinarily its “head”, or front end, is broad and rounded. By a muscular contraction, however the shape of the head can be made pointed and is thrust forward in the mud, when its normal contour is resumed. Then again comes the muscular contraction, the pointed head, and another thrust forward. This occurs over and over again. The contraction waves follow each other so quickly that the drilling process appears constant. The proboscis does not seem to be used in the actual drilling operation, but is kept probing for points of least resistance and turns aside at the slightest obstacle.