Annelida - Introduction
Annelida: History of the Classification; General Introduction.
ANNELIDA, a class of the sub-kingdom Annulosa, the title being derived from Lamarck's term Annelides (Annellus, a little ring), given to Cuvier's red-blooded worms. The latter were included by Linnaeus under his Vermes, along with intestinal worms, mollusces, zoophytes, and sponges. The labours of Pallas, Baster, Otho Fabricius, and especially O.F. Muller, enabled Gmelin, in the 13th edition of the Systema Naturoe of the great Swede, to make some improvements and many additions. Cuvier ranged the Annelida under his Articulata, giving them the chief position on account of their red blood; but they are now generally classified as a separate type below the latter. It would be out of place to enumerate all the advances that have occurred since Cuvier's time, but among those whose names stand prominently forward in this respect are Lamarck, De Blainville, Bosc, Audouin, Milne-Edwards, Duges, Mosquin-tandon, and De Quatrefages in France; Van Beneden, Morren, and D'Udekem in Belgium; gruithuisen, Oken, H. Rathke, Grube, Max Schultze, Hoffmeister, Hering, Kolliker, Schmarda, Keferstein, Ehlers, and Ratzel in Germany; Claparede in Switzerland; Malmgren, Metschnikoff, and Kowalevsky in Russia; Sars in Norway; Kinberg and Loven in Sweden; Delle Chiaje in Italy; stimpson, Leidy, A. Agassiz, and Verrill in North America; and Montagu, Dalyell, G. Johnston, J. R. Johnson, Williams, Huxley, Baird, and Ray Lankester in our own country.
The annelida may be described as bilaterally symmetrical animals, with flattened or cylindrical bodies, composed of numerous soft rings, or without such. The locomotive appendages (generally furnished with bristles) are not articulated. Nervous system consisting of a cephalic ganglion or pair of ganglia, connected on each side of the oesophagus with a chain of ganglia running along the ventral aspect. Mouth ventral; alimentary canal with an anus. Circulatory system with distinct vessels. The majority are small animals, but some reach the length of 6 feet and upwards, and are as thick as a finger.
In the present article the Annelida will be understood as comprehending the A. POLYCHAETA, A. OLIGOCHAETA, A. ONYCOPHORA, A. DISCOPHORA, and A. GEPHYREA, the first two being often placed together in the subclass Chaetopoda.
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Annelida - Table of Contents