An Attempt to re-classify the Rotifers. 

 By 



C. T. Hudson, l.I/.l>. 



FiVE-AND-FORTY years have elapsed since Ehrenberg published 

 his classification of the Rotifera, and his system still holds its 

 ground. The mere statement of the fact is high praise ; for what 

 have not classifiers altered, and attempted to alter, during the last 

 half century ? Not that his classification has escaped challenge. 

 It was sharply criticised in the ' Histoire naturelle des 

 Zoophytes^ by Dujardin, in 1841; and the author showed by 

 his criticism that he would probably have invented an excellent 

 classification, if he had only had the requisite knowledge. For 

 his arrangement of the Rotifers into great groups was excellent, 

 and he failed in his subdivisions, obviously from lack of per- 

 sonal acquaintance with the creatures he was classifying. 



Leydig, also, in his admirable treatise ' Ueber den Bau und 

 die systematische Stellung der Raderthiere,'' in 1854, pointed 

 out some of the obvious faults of Ehrenberg's system ; and 

 substituted for it a far inferior one of his own. 



Lastly, Dr. Samuel Bartsch, in a pamphlet on ' Die Rader- 

 thiere ' in 1870, and again in a larger treatise on the ' Rotatoria 

 Hungarise ^ in 1877, has essayed a new classification, which is, 

 I think, by no means a success. 



I propose now to point out, as briefly as may be, what seem 

 to me to be the chief faults in these four systems ; and then, 

 availing myself of all that has been already done, to see how 

 far the accumulated observations of the last forty-five years will 

 enable us to arrange the Rotifers in well-marked and fairly 

 natural groups. I am sanguine enough to think that this can 

 be done with a large proportion of them ; though there may 

 remain outstanding some genera, that can at the best have only 



VOL. XXIV. NEW SEK. A A 



