For example of the most crooked, or Azygobranchiate division of the Streptoneura, turn now to Fig. 33, in which we see a typical Gasteropod shell, _Murex ramosus_, the Branchy Murex, aptly enough named from the many prickly branches which beset it. These rough points are probably assumed for protective purposes; any animal that might wish to dine upon the _Murex ramosus_ would think twice before trying to swallow it--the morsel of shell-fish is so small, its shelly case so large and so prickly. If we look for its nearest English relative, that is _Murex erinaceus_, the Hedgehog Murex, or Sting-winkle. This, though a comparatively plain shell, has still enough rough ridges upon it to have secured it a comparison to the prickly hedgehog. Perhaps the most prickly member of the genus, however, is _Murex tenuispina_, sometimes called Venus' Comb, because the crowded parallel spines which decorate the elongated front of the shell somewhat resemble the parallel teeth of a comb. [Illustration: FIG. 33.--The Branchy Murex, _M. ramosus_, a typical specimen of the shell of the Carnivorous Gasteropods. _Sp._, spire or posterior end of the shell; _S_, siphon or anterior end of the shell. Fig. A, shows the mouth of the shell; Fig. B, the exterior only. Less than one-half the natural size.] How does the _Murex_ get its living? Let us notice the shape of the shell, drawn out to a point, at the end opposite to the spire. According to the older classification of the Mollusca, now somewhat fallen out of use, this point marks the shell as belonging to one of the Siphonostomata (shell-fish with a siphon at the mouth of the shell, _i.e._). These shell-fish are, with few exceptions, carnivorous; not that the siphon shape of the shell has any direct connection with the animal's way of feeding. Just as the snail files among soft vegetable substances, so the Murex and many of its relations file away much harder things. A Sting-winkle, or a Dog-whelk, can sit down over a helpless bivalve shell-fish, and patiently file away, until it has worked a neat round hole in the protecting shell of the latter. You may find, among the dead shells on any sandy part of the English coast, any number of bivalve half-shells with a neat little round hole in them, indicating unmistakeably how the tenant came to its death. There is some controversy as to the spot chosen by the assailant for its attack. Some authorities have stated that the predatory mollusc is so wise that it knows where to find a weak spot, and makes a hole just over some vital organ of the bivalve, or else above its adductor muscles, so that, when these are cut, the half-shells cannot be drawn tightly together and kept shut. Recently this has been denied, and statistics of the attacks of _Purpura_, the common small whelk, a relation of the _Murex_, on _Mytilus edulis_, the Common Mussel, have shown that the perforation occurs in every part of the shell. It is possible, however, that the