652 



DESCRIPTION OF 



{^Rotatoria. 



either a simple conical stomach fcoehgastrica), or else one produced 

 by a constriction of the alimentary canal ( gasterodela.J Two round 

 or ovate intestinal glands are also seen. The discharging opening is 

 at the base of the foot, upon the dorsal surface, which latter is 

 clearly indicated by the situation of the eyes, when present. The 

 ovarium developes but few large ova at a time ; two sexual glands 

 and a contractile vesicle exist in the genera Euchlanis, Monostyla, 

 Stephanops, and SqmmeJIa — the latter only in Metojndia, LepadeUa, 

 and Mastigocerca. They do not carry their ova externally. Traces of 

 a vascular system are seen in two species of Eiichlams, and perhaps 

 also gills in Dhiocharis, w^hilst the respiratory tube in Salpina and 

 EucManis must be considered as such. The nervous system is indi- 

 cated in ten genera by the presence of red visual points, whose 

 situation and number are useful in establishing generic characters ; 

 an evident cerebral ganglion (as a nervous layer to the eyes) is found 

 in Euchlanis, Monostyla, Mastigocerca , and Salpina. The genus Lepa- 

 della developes itself occasionally in such myriads, in stagnant water, 

 as to give a whitish turbidity to it. 



The genera are disposed as foUow : — 



No eyes, foot furcated Lepadella. 



lorica depressed Monostyla. 



Eyes 

 present. 



one eye 



(cervical.) 



foot 

 styliform 



lorica prismatic Mastigocerca 



foot -^ 

 furcate 



lorica gaping beneath Euchlanis. 



/ lorica horned Salpina. 



without horns Dinocharis. 



f foot styliform Monura. 



lorica closed 

 beneath j 



two eyes 



(frontal.) 



foot 

 furcated 



lorica compressed laterally or cylindrical. Colurus. 

 head not hooded Metopidia. 



lorica depressed ) 

 or prismatic 



, head hooded Stephanops. 



, four eyes, foot furcate Squamella. 



These genera are mostly included in the family BracJiioniem of 

 Dujardin. 



