174 THE MICROSCOPE. 



full of interest. He says, it is an animalcule so minute as to be with 

 difficulty appreciable by the naked eye, inhabiting a tube composed of 

 pellets, which it forms and lays one by one. . It is a mason, who not 

 only builds up his mansion brick by brick, but makes his bricks as he 

 goes on, from substances which he collects around him, shaping them 

 in a mould which he carries upon his body. 



The animal, as it slowly protrudes itself from its ingeniously-formed 

 mansion, appears a complicated mass of transparent flesh, involved in 

 many folds, displaying at one side a pair of hooked spines, and at the 

 other two slender short blunt processes projecting horizontally. As it 

 exposes itself more and more, suddenly two large rounded discs are 

 expanded, around which, at the same instant, a wreath of cilia is seen 

 performing its surprising motions. Often the animal contents itself 

 with this degree of exposure; but sometimes it protrudes farther, and 

 displays two other smaller leaflets opposite to the former, but in the 

 same plane, margined with cilia in like manner. The appearance is 

 not unlike that of a flower of four unequal petals, from which circum- 

 stance Linnaeus gave it the name ringens, by which it is still known. 



Below the large petals on the ventral aspect, and just above the 

 level of the projecting respiratory tubes, is a small circular disc or 

 aperture, within the margin of which a rapid rotation goes on. This 

 little organ, which seems to have hitherto escaped observation, he, 

 Mr. Gosse, can compare to nothing so well as to one of those little 

 circular ventilators which' we sometimes see in one of the upper panes 

 of a kitchen-window, running round and round, for the cure of smoky 

 chimneys. 



The gizzard, or muscular bulb of the gullet, is always very distinct, 

 and its structure is readily demonstrated. It consists of two sub-hemi- 

 spherical portions, or jaws, each of which is crossed by three developed 

 teeth, which are succeeded by three or four parallel lines, as if new teeth 

 might grow from thence. The teeth are straight, slender, swelling 

 towards their extremity, and pointed. These armed hemispheres work 

 on each other, and on a V-shaped or tabuliform apparatus beneath, 

 common to most of the Rotifera, but in this genus very small. 



The pellets composing the case are very regular in form and posi- 

 tion: in a fine specimen, about l-28th of an inch in length when fully 

 expanded, of which the tube was 1-3 6th of an inch, Mr. Gosse counted 

 about fifteen longitudinal rows of pellets at one view, which might give 

 about thirty -two or thirty-four rows in all. 



In November 1850, Mr. Gosse found & fine specimen attached to a 

 submerged moss from a pond at Hackney; this he saw engaged in 



