D. BRYCE OX A NEW CLASSIFICATION OF THE BDELLOID ROTIFERA. 71 



the species now assigned to it have of late years seemed to me to 

 represent the central group of the very heterogeneous crowd of 

 forms which the too elementary definition of " no eyes " has 

 caused to be associated with this name. For reasons which will 

 be later explained I am far from satisfied that the identity 

 of Ehrenberg's Callidiiuo elega7is, the species for which he created 

 the genus Callidina, has been rightly determined by any of the 

 authors who have hitherto accepted it, nor, although particularly 

 anxious to establish as many as possible of the old but too 

 scantily described forms, have I myself succeeded in finding it. 

 As to his next described species, Callidina rediviva, which would 

 seem to be a pellet-making form, I am in the same position. Of 

 six other species described by him after a long interval, three 

 are now recognisable, but belong to two very distinct groups, 

 (C.) alpium having four toes, and [C.) scarlathia and (C.) tetraodoii 

 having the foot ending in a sucker-like disc. Under these 

 circumstances I have felt myself at liberty to employ the familiar 

 name for those species which remain in the old genus after 

 relieving it of the most aberrant forms. The new definition is 

 perhaps somewhat too comprehensive still. The genus includes 

 three rather distinct groups of species which may be characterised 

 respectively as : 



1 . Rough-skinned. 



2. Smooth-skinned, short-footed, non-parasitic. 



3. Smooth-skinned, long-footed, and parasitic. 



For the rough-skinned and the parasitic groups I think it will 

 ultimately be desirable to provide separate genera. The second 

 group of smooth-skinned, short-footed, non-parasitic forms I 

 regard as generally representing the type of the genus Callidina. 



Subsection III., with toes bearing cup-like suckers or united to 

 form a broad disc or twin discs. Although the species included 

 in this subsection are relatively few in number, certain of them 

 have been more exhaustively studied than all the other Bdelloida 

 together. The majority are large forms, possessed of well-developed 

 coronae, and they usually inhabit ground-mosses and liverworts 

 of various kinds. But besides the moss-dwelling forms there are 

 two species which are parasitic in habit and very distinct in some 

 structural details, viz. Discopus synaptae Zelinka, and A^iomopus 

 telphusae Piovanelli. The genera Discopus and Anomopus are 



JouRN. Q. M. C, Series II. No. 67. 6 



