Ili/datinaea.'] iNFrsoRiAL animalcules. 627 



Besides the two families of Rotatoria, Flosculariens, and Meli- 

 certiens, constituted by M. Dujardin, lie makes but four others, 

 and one of these, " Albertietis," represented by a single genus 

 peculiar to his work. These four families are " Brachioniens,^' 

 " Fio'ciilariens," " Albertiens," and " Roti/era." The family 

 Rotifera comprises but two genera. Rotifer and Callidina, conse- 

 quently ail the genera of Ehrenberg yet undescribed, and which are 

 admitted by Dujiirdin, fall under the two families Brachioniens and 

 Furculariens. Excepting two genera, the last named family includes 

 several of Ehrenberg's Hydatinaea, whilst the other family Brachio- 

 niens is represented by examples taken from the families Brachionaea, 

 Eiichlanidota, and Hydatinaea, of Ehrenberg's arrangement. 



The great differences of classification adopted by the two natu- 

 ralists referred to, are traceable to the different systematic value 

 assigned by each to particular parts or organs, and especially to the 

 eye specks, the use of which in framing distinctions is entirely 

 ignored by Dujardin. 



Genus Enteroplea. — Without eyes or teeth; foot fork-like ; the 

 cilia of the vibratile organ disposed in bundles, implanted in semi- 

 globular muscles. Several longitudinal muscles move the body, 

 others the foot-like pincers. (Esophagus long, with a bulb or head 

 surrounded by a radiant (vascular 1) wa-eath ; alimentary canal 

 conical anteriorly, with two ear-like pancreatic glands ; posteriorly 

 it suddenly diminishes, and terminates where the muscles of the foot 

 commence. The propagative structures are a large ovarium, two 

 thin wedge-shaped glands, and a contractile vesicle. The vascular 

 system is indicated by many parallel transverse circular canals, and 

 a large tremulous organ, similar to a gill, near the contractile 

 vesicle. A brain-like knot, situated near the oesophagus, sends off 

 a thick tortuous thread along the dorsal surface to the second trans- 

 verse vessel, where the respiratory opening probably exists. Pos- 

 teriorly, near the alimentary canal, is a dark granular organ, whose 

 function is unknown. 



E. /lyalina. — Body conical, transparent, with a little forked foot. 

 Anteriorly, four longitudinal muscles reach to the middle of the 

 body, and one dorsal, one ventral, and two opposed lateral ones, are 

 also seen. Two internal short wedge-shaped muscles move the 



