W HEN Victor Hugo, in "The Toilers of the Sea," penned his immortal description of the combat between a man ami a "polyp," he rendered one of the most fascinating if not strictly credible accounts to be found in romantic literature. Unfortunately, Hugo was not a naturalist and his scientific knowledge was somewhat primitive; as a result both his description of the devil-fi sh and of the man-hunting attributes of his monster have no counterpart in fact. Still, imper fect as this description is,

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... t at least had the merit of giving publicity to a class of animals which would probably have remained little known to few other than professed naturalists, for, as it was once truthfully observed, it has done more to acquaint the world at large with the existence of cephalopods than all the The devil-fish-or octopus-and its allies compose a group of animals which in the language of science is termed the cephalopoda. The cephalopods are highly organized molluscs-being very close relatives to the clams, snails, slugs, etc.-and are distinguished pri marily by their tentacular sucker-arms arranged in a radial manner around the mouth. All are carnivo rous, and subsist chiefl y on fishes and crustaceans which they catch with the aid of these members. There is some evidence, however, that certain squids are part, if not wholly, vegetarian in their diet, for several large specimens captured off Catalina Island, California, were found to have their stomachs full of sea weed. The best known members of this group are the squid, storms. In this connection it may be observed that sperm whales live almost entirely on cephalopods which they destroy in countless numbers in their ex cursions through the open sea. The giant squid lives only in the deep sea and has never been seen alive near the waters of the shore. The common squids of our shores are not unlike the giants in appearance except for size. Rarely do they attain more than a foot and a half in length. They are rovers and often travel in shoals, following schools of young fishes or minnows. Often, however, a lone in dividual will stalk its prey, and as it swIms it presents some remarkable color changes. This peculiar property of changing its color, which is also shared by other members of the group, is due to pigment cells cover-1. The squid; photograph taken in a tidal pool. 2. Suckers on the tentacles of a squid. 3. The octopus, which is doubtless the devil-fish of tradition. 4. A cuttlefish, swimm.ng. 5. An artist's conception of the nature al1d capacity of the devil-fish (by Dore), now realized to ��tabsurd. 6. Baby squid, greatly enlarged The three best-known members, of the devil-f i sh tribe, as they'are and as they are not learned and careful writings of the men of science. Since this classic instance of the employment of these creatures as a;J. aid to excite the imagination, other fictionists with more elaboration, but les'> art, have continued to use this literary device; consequently the devil-fish and its allies have achieved an evil repu tation and are generally conceived to be the most fear ful and drea(lful of invertebrate animals. Naturalists, however, have a quite different story to tell; from them we learn that these monsters are not so hlack as they are painted. Their reports though less thrilling are none the less most interesting, and more over they reveal traits in these creatures which are among the most extraordinary to be found in the lower animals. the octopus and the cuttlefish; these three types which are often confused with. one another, have ul)doubtedly figured more largely in popular literature than any other. Yet it may be worth while to mention one which has achieved no little fame in tbe realm of poetry. This is the nautilus, a cephalopod which bears a beautiful shell of pearly iridescence. The squids range in size from the little sepiolas of an inch long to the giant Architeuthis; specimens of the latter having been found which were said to meas ure nearly fifty feet over the entire length of the body. These are the largest invertebrates known. They are, however, extremely rare, as very few have even been found; and even of these, none was in perfect condi tion due to the attacks of whales and the violence of © 1921 SCIENTIFIC AMERICAN, INC ing the entire surface of the body. These cells work somewhat after the principle of the pupil of the hu man eye. When the animal is colorless a dilation of these minute organs exposes a pigmented area; each chromatophore-as it is called-assuming a pin-point dot of a reddish brown, expands like an enlarging freckle until the edges meet. These changes can be produced almost instantly, from white to a deep brown or purple, or the reverse, and can be restricted at the will of the squid to different areas of the body, giving the animal a mottled appearance which enables it to simulate the pebbly bottom with astonishing realism. Perhaps few circumstances are more startling than one's first sight of the squid lying on the bottom after it has changed to a deep brown, contrasting strongly