62 d. bryce on a new classification of the bdelloid rotifera. 



Section Philodinaea. 

 Without eyes ...... Gen. CallicUna. 



With two eyes. 

 Eyes frontal : 



Foot thrice furcate ("cauda ter f ar- 

 eata ")..... Gen. Rotifer. 



Foot ending in two spurs and three 



toes ("caudae quinqueapicibus ") Gen. Actinurus. 



feyes dorsal : 



Foot simply furcate (" cauda sim- 



pliciter furcata '*)... Gen. Monolahis. 



Foot thrice furcate (" cauda ter fur- 

 cata") . . . . .Gen. Philodina. 



In the following year, 1831, Ehrenberg published a more 

 comprehensive arrangement (3), in which the Philodinaea were 

 advanced to the rank of a family, and this position was again 

 assigned to them in his great work of 1838 (4), based upon his 

 third and best-known system of classification. In these later 

 schemes the two genera Ty2)hlina and Hydrias were added to 

 the Family with the following characters : 



Without rostrum or spurs : 



Trochal discs on pedicels . . . Gen. Hydrias. 



Trochal discs without pedicels . . Gen. Ty^Mina. 



It has not yet been found possible to recognise any of the 

 species assigned to the genera Monolahis, Hydrias, and Typhlina, 

 and these genera have not been accepted by later Avriters, who 

 believe them to have been founded on imperfect observations 

 of animals which, if again seen, have been referred to other 

 groups of the Kotifera. The four genera, Callidina, Philodina, 

 Rotifer, and Actinurus, have fortunately proved to be recognis- 

 able, and the majority of the species, which have been discovered 

 since 1838, have been assigned to one or other of them. 



As in the classification of 1830, so in his later schemes, 

 Ehrenberg distinguished the four genera last named principally 

 upon characters afforded by the presence or absence of eyes, and, 

 when present, by their position, either in the front of the head 

 or in the neck. As a quite subsidiary character, to distinguish 

 Rotifer from Actinurus, and Philodina from Monolahis, he made 



