In the old days of the Caesars, a Greek or Roman house-wife who was accustomed to see the cuttle, the squid, and the octopus daily exposed for sale in the markets, would of course have laughed at the idea of mistaking the one for the other; but there are comparatively few persons in our own country, at the present day, except those who have made marine zoology their study, whose ideas on the subject are not exceedingly hazy. This want of technical knowledge is not confined to the masses; but is common, if not general, amongst those who have been well educated, and is frequently apparent even in leaders in the daily papers--the productions, for the most part, of men of receptive minds, trained discrimination, and great general knowledge. As the subject is one in which I have long felt especial interest, I venture to hope that I may succeed in making clear the difference between the eight-footed octopus and its ten-footed relatives, and thus enable the reader to identify the member of the family from which we are to strip the dress and "make up" in which it masqueraded as the Kraken, and cause it to appear in its true and natural form. One of the great primary groups or divisions of the animal kingdom is that of the soft-bodied mollusca; which includes the cuttle, the oyster, the snail, &c. It has been separated into five "classes," of which the one we have especially to notice is the _Cephalopoda_,[5] or "head-footed,"--the animals belonging to it having their feet, or the organs which correspond with the foot of other molluscs, so attached to the head as to form a circle or coronet round the mouth. Some of these have the foot divided into eight segments, and are therefore called the _Octopoda_:[6] others have, in addition to the eight feet, lobes, or arms, two longer tentacular appendages, making ten in all, and are consequently called the _Decapoda_. [5] From the Greek words _cephale_, the head; and _poda_, feet. [6] From _octo_, eight; and _pous_ (_poda_), feet. Of the ten-footed section of the cephalopods, there are four "families;" two only of which exist in Britain--the _Teuthidae_, and the _Sepiidae_. The _Teuthidae_ are the Calamaries, popularly known as "Squids," and are represented by the long-bodied _Loligo vulgaris_, that has internally along its back a gristly, translucent stiffener, shaped like a quill-pen; from which and its ink it derives its names of "calamary" (from "_calamus_," a "pen"), "pen-and-ink fish," and "sea-clerk." The _Sepiidae_ are generally known as the Cuttles proper. As a type of them we may take the common "cuttle-fish," _Sepia officinalis_, the owner of the hard, calcareous shell often thrown up on the shore, and known as "cuttle-bone," or "sea-biscuit."