ENTOZOA, (rrroc, intus, animal,) o-rgoyyon, ITXCLTNIOLI, c, Arist. et Antiq. Vers Intestinaur, Cuv.
1:ntehttintha, Splanchnelmintha, Zeder.
The term EnrozoA, like the term Infitsoria, is indicative of a series of animals, associated together chiefly in consequence of a similarity of local habitation ; which in the present class is the internal parts of animals.
In treating therefore of the organization of these parasites, we are compelled to consider them, not as a class of animals established on any common, exclusive, or intelligible cha racters, but as the inhabitants of a peculiar dis trict or country.
They do not, indeed, present the types of so many distinct groups as those into which the naturalist finds it necessary to distribute the subjects of a local Fauna, yet they can as little be regarded as constituting one natural assem blage in the system of Animated Nature. And it may be further observed that as the members of no single class of animals are con fined to one particular country, so neither are the different natural groups of Entozoa exclu sively represented by species parasitic in the interior of animal bodies. Few zoologists, we apprehend, would dissociate and place in sepa rate classes, in any system professing to set forth the natural affinities of the animal king dom, the Planarie from the Trematoda, or the Vibrionidie from the microscopic parasite of the human muscles.
In the present article it is proposed to divide the various animals confounded together under the common term of Entozoa or Entelmintha into three primary groups or classes; and, as in speaking of the traits of organization common to each, it becomes not only convenient but necessary to have terms for the groups so spoken of, they will be denominated Pratel mintha, Sterelmintha, and Calelmintha respec tively.
It may be observed that each of these groups, which here follow one another in the order of their respective superiority or com plexity of organization, hal been indicated, and more or less accurately defined by pre vious zoologists. After the dismemberment of the Injitsoria of Cuvier into the classes Palygastrica and Rotifcra, which resulted from the researches of Professor Ehrenberg into the structure of these microscopic beings, there remained certain families of Animalcules which could not be definitely classed with either : these were the Cercariade and Vibrio nide. Mr. Pritchard, in his very useful work
on Animalcules, has applied to the latter fli ntily the term Entozoa, from the analogy of their external form to the ordinary species of intestinal worms ; and it is somewhat singular that a species referrible to the Vibritniidx should subsequently have been detected in the human body itself. Premising that the tribe Vibrionide as at present constituted is by no means a natural group, and that some of the higher organized genera, as Anguillula, are re ferrible to the highest rather than the lowest of the classes of Entozoa, we join the lower organ ized genera,which have no distinct oviducts, and which, like the parasitic Trichina, resemble the fintal stage of the Nematoid worms, with the Cercariade, in which the generative apparatus is equally inconspicuous; and these families, dismembered from the Infusaria of Lamarck, constitute the class Protelmintlia, the first or earliest forms of Entozaa.
The second and third classes correspond to the two divisions of the class Intestinalia, in the Rbgne Animal' of Cuvier, and which are there respectively denominated ' Vers Intesti naux Parenchymateux,' and Vers Intestinaux Cavitaires."The characters of these classes will be fully considered hereafter ; and in the mean while but little apology seems necessary for in venting names expressive of the leading distinc tion of each group as Latin equivalents for the compound French phrases by which they have hitherto been designated. ENAerc appears to have been applied by the Greeks to the in testinal worms generally, as Aristotle speaks of ixihnOic vrTzrtraI, Intestinalia lata, and iNanDic crrgoyyacti, intcstinalia teretia. In framing the terms Sterclmintha and CalcImin tha, from Awn crrigm, a solid or parenchy matous worm, and ain't xen)o), a hollow or cavitary worm, I follow the example of Zeder, and omit the aspirate letter. It may be ob served by the way that Zeder's term Splanehnel mintha, besides including animals which are developed in other parts than the viscera, is, like the term Entozoa, open to the objection of being applied to a series of animals which, ac cording to their organization, 'belong to distinct classes.