ON THE CLASSIFICATION OF THE EOTIFERA. 



29 



4. Incudate (fig. 32). 



Mallei evanescent ; rami highly developed into a curved forceps ; fulcrum stout ; as 

 in Asplanchna Ebbcsbomii. 



5. Uncinate (fig. 27). 



Unci 2-toothed ; manubria evanescent ; incus slender ; as in Stephanoceros 

 Eichhomii. 



Fig. 30.— Sub-malleate. 



. 31.— Forcipate 



Fig. 32.— Incudate. 



6. Hamate (fig. 28). 



Rami sub-quadrantic, each crossed by two or three teeth ; manubria evanescent ; 

 fulcrum rudimentary ; as in Philodina roseola. 



7. Malleo-ramate (fig. 26). 



Mallei fastened by unci to rami ; manubria 3 loops soldered to the unci ; unci 3- 

 toothed ; rami large, with many striae parallel to the teeth ; fulcrum slender ; as in 

 Mcliccrta ringens. 



Now, the seven Rotifera, made use of above to yield examples of typical tropin, are 

 very distinct from each other, and show that the form of the tropin is one good charac- 

 teristic for separating the families. But a difference in the shape and disposition of the 

 corona, and of its ciliary wreath, generally accompanies a difference in the manducatory 

 organs ; and the three together will serve as good guides to a division of the four orders 

 into families. 



In one of the sub-divisions of the Ploima, however, the corona, ciliary wreath, and 

 tropin are often difficult of determination ; but just where these guides desert us, a new 

 character, viz. the lorica, comes to our aid, and shows such well-marked differences in 

 shape and structure, as to enable us to divide this sub-order (the Loricata) into fairly 

 natural groups. The Loricata are so called from the integument of the body ; which, 

 from the distribution of chitine throughout the tissue, is hardened into a stiffened coat 

 or shell (lorica, a coat of mail) inclosing, more or less completely, the internal organs. 

 In the Il-loricata the integument is soft and flexible ; but there is, unfortunately, no very 

 sharp division between the two sub-orders in this respect ; as every variety of integu- 

 ment exists, from the hard, dense coat of Dinocharis, to the tough yet flexible covering 

 of Battulus, and the perfectly soft cuticle of Albcrtia. 



The following scheme, then, is an attempt to divide the four orders of Rotifera into 

 families, by means of the various characters which I have just detailed : of course, there 

 are some genera which do not readily fall into the arrangement ; but this is only what 

 is certain to happen to every possible scheme of classification. 



Such difficulties must attend every attempt to marshal Nature's endless varieties into 



whole apparatus looks like one forceps within another. 

 term virgate will be applied. 



To this variety of the forcipate tropin the 



