22 WHEEL AMIMALCULES. 



and swim about in company, then apparently to take counsel 

 together, select a particular spot, and all of a sudden attach 

 themselves in a group, where they stretch up to their full extent 

 and begin bowing and salaaming to one another. in the most 

 polite and courteous manner imaginable. 



Next we have a division of these animalcules, in which the 

 surface of the body is covered with an array of bristling spines 

 and hooks, by means of which their owners creep and climb about 

 amongst aquatic plants ; in another group we meet with a 

 singular apparatus, consisting of a circlet of bristles -which sur- 

 round the mouth, and has hence received the name of teeth, but 

 which appear to be organs of prehension rather than of any sort of 

 mastication. Another tribe presents us with animalcules having 

 an oval body and a long flexible neck, which the little creatures 

 throw into graceful curves, like so many microscopic Swans, after 

 which, indeed, they are named, one species giving us a veritable 

 representation of that rara avis, the " Swan with two necks !" 



The Rotifera or Wheel Animalcules are, as we have already 

 intimated, much more highly endowed than any of the preceding 

 tribes, and excepting as to size, are not to be classed amongst the 

 animalcules at all. But they are much too curious and interest- 

 ing to be omitted from our survey of the various microscopic 

 forms of life, and are therefore admitted here to the place which 

 they occupied before their true position in the animal series was 

 known. The discovery of the Rotifera was one of the earliest 

 results of the application of the microscope to the study of these 

 minute forms of life, nor is this at all remarkable, seeing that 

 some of the species are as much as the twelfth of an inch in 

 length, and readily descemible therefore by the naked eye. 



It is perhaps even yet premature to assume that the true 

 position of the Rotifera has been satisfactorily ascertained ; but 

 there can be no doubt that their true affinities are with the arti- 

 culate sub-kingdom, in which they are now generally placed. The 

 details of structure vary greatly amongst the different species ; 

 but in all of them it is exceedingly complicated, and shows a 

 great advance upon the simple forms of life with which they 

 were formerly associated. In all there is a more or less distinct 

 head, furnished with eyes and a mouth, from which a passage 

 leads to a powerful masticating apparatus, in close proximity to 

 the stomach, from which, in many species, proceeds an alimen- 



