61S DESCKiPTiox OF [Rotatoria. 



with four muscles ; two jaws with teeth ; two semi-spherical pan- 

 creatic glands ; and an ovarium, with a single ovum ; anteriorly, 

 upon the ventral surface, are two respiratory tubes. 



TuBicoLARiA najas. — The jaws have four teeth, and the respi- 

 ratory tubes are hairy anteriorly. It is described fully in the 

 account of the genus, and figs. 3/9 to 382 will illustrate it; 381 

 represents the animals of natural size, as found attached to the 

 roots of Lemna polyrhiza, with those of the following genus ; 

 379 represents an animalcule within its case, the rotatory organ 

 withdrawn ; 380, another animalcule extended, and without its 

 lorica. Fig. 382 shows the a3sophagus, with the jaM's and teeth 

 separate. Length l-36th. 



Genus STErHANOCEEOS. — The crown-ivheel Animalcules have one 

 eye, and a rotatory organ, deeply divided into lobes, and furnished 

 with verticellate cilia: this organ performs the office of locomotion. 

 Alimentary canal simple, with a stomach and small rectum ; the 

 oesophageal head has jaws, with four teeth ; before it is a large 

 crop-like structure, and two glands at the stomach ; the ovarium 

 developes only a few ova at a time ; perhaps two male glands exist 

 at the commencement of the row of tremulous gills ; a red visual 

 point, with a row of nervous ganglia, in pairs, are visible at the base 

 of the rotatory organ ; young animalcules possess a small glandular 

 dark body internally. 



S. Hicliliornii. — The case transparent, like glass ; rotatory organ 

 has five lobes or arms, each furnished with fifteen verticellate cilia ; 

 these arms act as a prehensile instrument occasionally, and are 

 spread out, as shown in the engraving, fig. 383, which represents 

 a full-grown animalcule, with four ova within it ; tM'o have the 

 young developed, which are only expelled when in this state ; hence 

 Ehrenberg considers this creature viviparous. In this figure the 

 eye and gills are visible, and over the latter the ganglia. The case 

 is difficult to be discerned under the microscope, from its very 

 transparent nature, unless indigo is mixed with the water. Length 

 l-3Gth. 



Genus Limnias. — Eyes two; case {urceolus) solitary; rotatory 

 organ two-lobed when full-grown, being then constricted in the 

 middle ; alimentary canal simple, terminating at the base of the tail ; 



