ROTIFERS. 



455 



of the wheels, it passes through a funnel as it were to the 

 mouth, which is situated rather lower down, and where 

 the food is crushed "by teeth placed on the plates of the 

 jaw, with a hammer-like action ; from this point it passes 

 through the alimentary canal for the sustenance of the 

 animal. 



BRACHION.EA. Ehrenberg's genus Brachionus, " Spine- 

 bearing animalcules/' belonging to the Rotifer ce, are truly 

 interesting, from their very perfect and complex orga- 

 nisation. Some are entirely enclosed in a horny covering, 

 others only partially covered. Their structure, so beau- 

 tiful and symmetrical, has always made them favourites 

 with those who delight in microscopical studies. Bra- 

 chionus striatus, " Striped shell animalcule " (No. 3, fig. 

 228), of an elegant, jug-like form, has the transparent 

 coat or carapace, striated and scalloped out at the upper 

 part ; through which the citron- 

 coloured inhabitant protrudes itself. 

 Two hornlike processes are appended 

 to its under-side. As occasions re- 

 quire, it sinks firmly and securely 

 within its crystal home, which is suffi- 

 ciently transparent to permit a view 

 of its organisation. Its progress is 

 effected by means of ciliary processes. 

 Brachionus Pala, or Amerce Cervi- 

 cornis, "Bent horn animalcule," is 

 possessed of double rotatory organs, 

 and four long processes, which project 

 above the external coat. It measures 

 theOOthpart of aninch. Brachionus 

 Ovalis, " Egg-shaped brachionus," is 

 remarkable for the strength > of its 

 transparent coat, which is beyond 

 that of other horny creatures. Its 

 projecting tail, as well as head, is at 

 pleasure withdrawn into its very 



strong case. Brachionus Dentatus, i, Brachionus Ovalis, closed. 

 *' Toothed brachionus." This active, 2 > Cilia displayed, 

 bright pink-eyed little creature, the 90th part of an inch 

 in size, is apparently enclosed in a two-valved shell, having 



Fig. 229. 



