This is only one of the many examples that might be given to illustrate this curious feature of the deep-sea Crustacea. Among the crabs alone we have such forms as _Galathodes Antonii_, _Pachygaster formosus_, _Dicranodromia mahyeuxii_ covered with a fierce armature of spines or bristles; but there are nevertheless some species in which this character is not particularly noticeable, and in these we usually find some other protection against their enemies. An interesting example of this has been described by A. Agassiz in a crab allied to the Maiadæ, ‘in which the dorsal face appears like a bit of muddy area covered by corals, with a huge white arm resembling a fragment of an Isis-like gorgonian.’ It is evident that this is a case in which the animal is protected by its resemblance to the surroundings. The hermit crabs of the abyss, too, are not usually characterised by any very great development of spines. They find their protection in the shells they inhabit. Some of the deep-sea hermit crabs carry about with them on their shells a sea anemone, as we find to be frequently the case among the shallow-water species. _Pagurus abyssorum_, from a depth of 3,000 fathoms, is an example of this. In cases where there is a scarcity of gasteropod shells the hermit crabs are obliged to find some other form of protection for their bodies. The ‘Blake’ found in the West Indies a hermit crab that had formed for itself a case of tightly compressed sand, and another curious form, named _Xylopagurus rectus_, makes its home in pieces of bamboo or in the holes in lumps of water-logged wood. The last group of the Arthropoda we need refer to is that of the Pycnogonida, those curious creatures seemingly made up entirely of legs, and by some naturalists considered to be related to the Crustacea and by others to the scorpions and spiders. Like the Brachiopoda the Pycnogonida are not usually found in greater depths than 500 fathoms. Out of the twenty-seven known genera, only five extend into the abyss, and not one of these can be called a true deep-sea genus. There are three genera, _Nymphon_, _Collosendeis_, and _Phoxichilidium_, that show a very wide distribution over the floor of the ocean, and are capable of existing at the greatest depths, and of these the species of the genus Nymphon have a truly remarkable range extending from the shore to a depth of 2,225 fathoms. ‘As a rule,’ says Hoek, ‘the deep-sea species are slender, the legs very long and brittle, and the surface of the body smooth.’ They have further, either no eyes at all or rudimentary eyes without pigment, and in many cases—as, for example, _Collosendeis_—they are distinguished for reaching to a gigantic size compared with their shallow-water relatives.