354 0. T. HUDSON. 



Fam. 2. Melicertadse (fig. 9). 



Mouth lateral ; wreath two marginal curves nearly sur- 

 rounding the head with mouth between; trophi malleo- 

 ramate. 



Order II. — Bdelloida. 



That swim and creep like a leech ; foot retractile, jointed, 

 telescopic, termination furcate. 



Fam. 3. Philodinad^ (fig. 13). 

 Trochal disc two transverse circular lobes; wreath two 

 marginal curves on each lobe with mouth between ; or trochal 

 disc of one lobe ventrally furred with cilia ; trophi ramate. 



Order III. Ploima. 

 That only swim. 



* Il-loricated. ' 



Fam. 4. Hydatinadse (fig. 1). 



Trochal disc transverse with ciliated prominences; wreath 

 double ; trophi malleate ; brain small, not sack-like ; foot 

 furcate. 



Fam. 5. Synchsetadse (fig. 3). 



Trochal disc rounded ; wreath of interrupted curves, sur- 

 rounding the head ; trophi virgate ; foot absent, or minute. 



Fam. 6. Notommatadse (fig. 4). 



Trochal disc oblique ; wreath of interrupted curves and 

 clusters ; trophi virgate or forcipate ; brain large, sack-like ; 

 foot furcate. 



which I have divided the Rotifera, no less than eight contain species of which 

 the males have been seen (see Fig. 15) ; and in the remaining four the 

 sexual organs exactly resemble those of the females in the other eight families. 

 That males will be ultimately discovered in the four families where they are 

 at present unknown, I have little doubt. 



Fig. 1 5 contains the male of one species only in each of the above eight 

 families ; but the males of many more than these have been observed and 

 figured. 



