INIYRIAPODA, (from the Greek kceetat, ten thousand, i.e. numerous, and srous, a foot,) the name of an important and highly interest ing class of articulated animals, intermediate in their structure and appearance between the Annelidans and the Insects, properly so called ; approximating the former in the worm-like form of their bodies, which are composed of a great number of rings or seg meats, and likewise allied to the latter by the construction of their jointed locomotive legs ; these, however, instead of being only six in number, as in the true Insects, are, in the Myriapoda, always at least twelve, and fre quently extremely numerous, being appended to all the segments of the elongated body, whence the names " Centipedes" and " Mille pedes," by which these creatures are commonly designated. All the members of the class are apterous ; they exhibit externally a succession of cylindrical or compressed rings, each of which sustains one or more, frequently two pairs of jointed feet, all of very similar con struction, being generally terminated by a single sharp claw. There is no consolidation of the anterior segments into a thorax resembling that of the Insecta, although many celebrated Entomologists are. disposed to regard the three anterior rings as the representatives of the tho racic segments. Upon the head are placed two antennae or feelers, which, in one large group, are short, stunted, and composed of seven articulations, whilst in others these organs are long and setaceous, presenting a much greater number of distinct joints. Compound or simple eyes, allied in their structure to those of Insects, are generally, but not always, pre sent. The mouth is formidable, and, in many respects, resembles that of Insects, being fur nished with strong mandibles, adapted to de vour either animal or vegetable substances. All the species breathe air by means of lateral stigmata and tracheal tubes, a circumstance whereby they are at once distinguishable from the CRUSTACEA. Their jointed legs remove them from the ANNELIDA, while they differ from the Insecta in many important particulars, but more especially in the progressive growth of their bodies, by the production of new seg ments, and the development of additional loco motive limbs, the number of which increases with the age of the animal, while, on the con trary, in Insects, the segments that existed at birth are found to coalesce into a smaller number, and the prolegs of the larvee become obliterated when the Insect attains its complete hexapod condition.
All the Myriapoda are terrestrial in their habits, lurking beneath stones or in the crevices of houses. Many of them inhabit decaying timber, or are found beneath the bark of trees, where they devour such vegetable substances as are adapted to their support ; or, in the case of the more highly organized species, wage war against other animals, upon which they feed.
The classification of the Myriapoda has hi therto been and still is exceedingly imperfect and unsatisfactory, apparently in consequence of their very wide distribution and the general similarity of their appearance. Our country man, Dr. Leach, in his zoological miscel lany, was one of the first who gave a general arrangement of these animals, which was adopted by Latreille ; but he appears only to have examined the European species. In Griffiths' Translation of Cuvier's Animal King dom, Mr. J. E. Gray. of the British Museum.
gave the figures of some exotic genera; hut of these the Editor left the descriptions very im perfect, and only made slight references to them in the explanations of the plates. Since thit time Dr. J. F. Brandt published a mono graph of the Myriapoda chilognatha,* in which he pointed out several new genera and re-named many, previously established by Mr. Gray. More recently M. P. Gervais has pub lished his studies on Myriapods,t consisting of a revision of the class and a list of the species, but having overlooked the slight notes given of Mr. Gray's genera, has in one or two instances been led into error. Under these circumstances it is, with very great satisfaction, that we are able, by the permission of Mr. Gray, who has kindly placed his manuscript at our disposal, to lay before our readers the following review of the entire class.