342 



C. T. HUDSON. 



on the whole it would seem best to use this characteristic as 

 sparingly as possible, and then only when the structure has 

 been thoroughly made out. 



If we now turn to the genera to see how far Ehrenberg's 

 system has brought similar forms together, we find fficistes 

 (which greatly resembles Melicerta (fig. 9)) separated from 

 its kinsfolk, and classed with animals some of which are not 

 Rotifers at all; Conochilus and Ptygura being in the 

 same predicament. 



Pig. 9. 



Fig. 10. 





StelsKaavotcros 



Pig. 9.— «. Principal ciliary wreath, b. Secondary ditto, c. Antenna. 

 Pig. 10. — b. Secondary ciliary wreath, d. Cephalic ganglion, e. Eye. j. 

 Stomach. /. Anus. n. Contractile vesicle, o. Ovary, f. Ovum. r. Poot. 



Worse than this, Stephanoceros (fig. 10) and Floscularia 

 (fig. 11) are placed in the same family with Melicerta (fig. 9) 

 and Limnias. Now the former pair differ from the latter most 



