INFUSOKIA. 475 



They differ from the SdjlonycJiice, in having tlie 

 soft body covered with a ])hite of crystal mail, hard 

 and inflexible, much like the shield of a Tortoise. 

 Several species have this glassy shield marked -with 

 delicate lines running lengthwise; sometimes in the 

 form of parallel ridges, as in a little species found in 

 infusions (perhaps E. cliaron /) at others foi-ming rows 

 of minute round knobs, as E. truncatus^ the species 

 now before us. The shield is ample, considerably 

 ^..^--j^iv^stv;^^ overlapping the soft body ; 



xT^ ^^^^^/^ ^^ rises into an arched 



'w^^^BI^^^^^^^^I^.'-'^ form in the centre ; and 



^irr^^^T ^i^^ ^ ^ ^—'^T^ is more or less round or 



^%rT^ ^,^,;^^''''°y^^^~^ oval. The mouth is ob- 



'^7^|T|TT\j\\^ — '\^;i/\^ ^v lique, and extends a long 



\>^ ...... ^^.,,^ \^ ^^,_^^ down the under sur- 



and fine cilia, whicii also spread over the front. The 

 organs of motion are, as before, long styles, pointed and 

 rather stiff processes, which project from beneath the 

 shell backwards and downwards, and soft hook-like 

 nncini which are set chiefly near the fore part of the 

 inferior surtace. In the species before us, these are 

 about six or seven in number, but in E. charon they 

 are more nnmerous. The twinkling rapidity with 

 which these little feet are applied to th.e surface in 

 crawling affords a pleasing sight; particularly when 

 the animal is running back-downwards on the upper 

 glass plate of the live-box. Some species have bristles 

 (or setoe) affixed to the hinder part of the shell, from 

 which they diverge. In E. trnncatus these are four, 

 but they are wanting in E. charon. The body displays a 

 mass of granules, vacuoles, and vesicles of different sizes. 



