Many of the univalves are flesh eaters, preying upon others of their kind. They have a remarkable tongue (Fig. 96) for the purpose, in fact, the teeth are upon the tongue in sawlike rows. The tongue, which is called the lingual ribbon, is ribbon shaped, long and slender, and is really a soft, pliable saw with which the animal bores into the hardest shells of the helpless clams. In strolling alongshore a large majority of the "dead" clam shells found bleaching in the sun, where they have been washed by the sea, will be seen to contain a circular hole of perfect symmetry (Fig. 97). This has been made by the boring, sawlike tongue of a univalve, which, after gaining an entrance into the tightly locked shell, deliberately sucked it out. It is interesting to note the location of this hole, which is invariably over the softest and plumpest part of the victim, near the lungs, showing that the cannibalistic univalve is very clever in its mode of attack. [Illustration: FIG. 97.--Clam shell bored by a univalve.] While the oyster deposits vast quantities of eggs, which float out into the water to be destroyed by other animals, many of the univalves protect their eggs in remarkable cases. I have often found on the Florida Reef strings (Fig. 98) of singular objects which resembled sections of a yellowish cylinder connected by a little cord. Each section is an egg case, or capsule, and contains many shells, the entire chain being two or three feet in length. This becomes tangled in the coral or seaweed, and holds the young shells, all of which escape through a little door in each section. [Illustration: FIG. 98.--Egg case of a conch.] Other shells, as the whelk (Fig. 99), deposit their egg cases in heaps or mounds. They are soft and spongelike, and are often mistaken for sponges when divested of their shells and cast ashore. Perhaps the best-known egg case is that of the common Natica, which forms a singular object called the "sand collar" (Fig. 100). The animal molds this collar out of fine sand with its foot, and deposits its eggs in the interior, all being cemented or glued together in a solid mass. We shall find that certain birds deposit their eggs in the nests of others, so saving the wearying process of hatching. A certain shell, called Nassa, has a similar habit. At times it deposits its eggs on the collar nest of the Natica. [Illustration: FIG. 99.--The whelk: _A_, living shell; _B_, empty shell; _C_, egg case.] [Illustration: FIG. 100.--Egg case of the Natica.]