Octopis, Or Ponlpe, a cephalopod mollusk, having a round purse-like body, without fins, and eight arms united at the base by a web, by opening and shutting which it swims backward, after the' manner of the jelly fishes. Each arm has a double alternate series of suckers, by which they seize their prey, and moor themselves to submarine objects. Swimming is also effected, backward, forward, or sidewise, by jets from the siphon, which may be turned in any direction; they can also crawl, looking like tipsy spiders, on their long flexible arms, in the manner shown in the third engraving. They are solitary, active, and voracious, seeking their food chiefly at night. They are the polypi of Homer and Aristotle. There are more than 40 species of octopods, found principally in the temperate and tropical seas, though some are met with in cold waters; they vary in size from an inch to 5 ft. in length of body, the arms being as much more. The common poulpe (0. vulgaris), of the European seas, has the body about as large as the clenched fist, with the arms expanding 3 or 4 ft.

The 0. tuberculata of the Mediterranean has a rough body about 5 in. long, and the arms 20 to 24 in.; it is often exposed for sale in the markets of Naples and Smyrna. Species of the same size abound in the Pacific, and are eaten in the Hawaiian and other islands, and in the East Indies. In tropical America they grow very large; one was found dead on the beach at Nassau, Bahamas, 10 ft. long, each arm measuring more than 5 ft., and estimated to weigh about 250 lbs.; and they are believed to exist there even larger than this. In cold waters they are small and not to be feared by man; but in the tropics, as on the coast of Brazil, the large species are very powerful and dangerous.

Common Poulpe (Octopus vulgaris).

Common Poulpe (Octopus vulgaris).

Octopus tuberculata.

Octopus tuberculata.

An Octopus crawling.

An Octopus crawling.

The common poulpe of the French coast has given rise to the mythical " devil fish" introduced by Victor Hugo in the "Toilers of the Sea," The novelist has mixed up a polyp and a poulpe, misled by the name given by Aristotle, and thus manufactured an impossible creature. The kraken of the Scandinavian nations is a mythical immense octopod, for which the recent discovery of a gigantic cephalopod on the coast of Newfoundland seems to afford a foundation in truth. (See Squid.) The genus eledone differs from octopus chiefly in having only a single series of suckers on each arm. All the species have an ink bag, by the contents of which the surrounding water is discolored, enabling them to escape their cetacean and other enemies. For details of structure, see Cephalopoda. - The only species known on the American coast, north of Cape Hatteras, is the one discovered in 1872 in the deep waters of the bay of Fundy by Prof. Verrill, and named by him octopus Bairdii; several, all males, were dredged during that summer in 75 to 200 fathoms, on shelly, muddy, and sandy bottoms.

Octopus Bairdii (life size).

Octopus Bairdii (life size).

The largest had a body 2 in. long and 1¼ in. wide, with arms 2¼- in. long; the color pale bluish white, translucent, with specks of light and dark brown. The body was short and thick, dotted with erectile tubercles, broadly rounded posteriorly; head almost as broad as body, swollen and rough about the eyes; arms of about equal length, relatively short, stout, and tapering, and webbed for the basal third. Each arm had two rows of 00 to 65 acetabula or suckers; the right arm of the third pair, for about a third of its length, was modified into a large spoon-shaped organ for reproduction, evidently not to be detached from the animal, as in many male cephalopods. The females, in this class generally by far the more numerous, were not seen, but were probably considerably larger than the males. Several were kept in confinement in tanks, and were most active at night. It was seen that when they were swimming by the basal web and the siphon, after each contraction of these parts and during the motion backward, the arms were held straight forward in a compact bundle; the only way in which they could swim forward seemed to be by ejecting jets of water from the siphon curved backward.

The southern American species are very much larger, and very different.