BRA CHIONYEA, a family of animals belonging to the order Rotifera. It embraces a large number of species formerly included under the genus Brachionus. It is distinguished from other families of Rotifera . by the possession of two rotatory organs, and a lorica or shell. The wheels, or rotatory organs, are apparently composed of five parts, three of which are central, and two lateral ; the latter of which alone form the true rotatory organs, the others being only ciliated frontal portions. Some have two setae proceeding from the rotatory apparatus, as in Syneketa. The jaws are supplied with teeth and four muscles. They are supplied with biliary glands and ovary, male organs, and a contractile vesicle. Ehrenberg regards a red spot in them as indica tive of the presence of a nervous system.
This family comprises the following genera :—Plerodina, Anourella, Brachionus, Lepadella, Euchlanis, Ditiodiaris, Salpina, Colmella,
.Rutulus, Polyarthra.
Ehrenberg makes seventeen genera ; but Dujardin has reduced the number to ten, on account of the insignificant character)) on which Ehreuberg's genera are founded.
Brachionus may be taken as a type of the family, and B. urceolaris is one of its most characteristic species. The genus Brachionus has a single eye (d), and a furcate foot or tail (t). It has a reddish colour, the shield smooth, with six short spines in front ; the posterior extremity rounded. The jaws have each five teeth. Both male and female organs are present. It is a very common species in both brackish and fresh waters. Dujardin says he has constantly found it in the cisterns of the Jardin des Plantes, in Paris, and especially in that in which the aquatic plants grow. A few yearn ago the waters of the Serpentine, in Ilydo Park, swarmed with this species, and it is very