TEE INFUS0BIAN8. 



11 



ooze. Chalk is largely made up of the calcareous shells of 

 Foraminifera; before it became hardened into rock-masses 

 it was a kind of Foraminifer- 

 ous ooze. 



Those Rhizopods which se- 

 crete a silicious shell are called 

 Radiolaria. A few (Fig. 6) 

 live in fresh-water ponds, but 

 the majority live in the sea. 

 Their shells possess wondrous 

 beauty and variety of orna- 

 mentation. 



Some Ehizopods are known 



, T 1 J, Tin 1 Fig, 6.—Actmosphrerium, a Radiola- 



tO develop from little monad- rian, o, a morsel of food drawn 



1-1 ^ ^j 1*1 into the cortical layer 6: c. central 



like or round germs, which parenchymatous mass of body: d, 



■mnvfi flVinnf hv mpmio of fwn some bails of food-stuff in the lat- 



mOVe aOOUl Oy means OI two ter;e, pseudopodla of the cortical 



little active threads or tails.* i^y«''- Highly magnified. 



CL.4.SS II. — GREGfAEINIDA. 



General Characters of Gregarines. — Tliese may be best 

 defined as parasitic, worm-like Amoebse. They are long 

 and slender, of quite definite flattened or cylindrical form 

 (Fig. 7) to adapt them to their parasitic life. Tlie largest 

 kind {Gregarina gigantea) is like a piece (;f fine thi-ead, 

 half an inch long; it lives in the intestine of the lobster. 

 Most Gregarinse are very minute, and are parasites, living 

 in the digestive canal of insects. 



Class III. — Infusoria. 



General Characters of Infusoria. — If we allow a little dried 

 grass or hay or a jjiece of fish to stand in a glass of water 

 for a day or two, thus making what is called an infusion, 

 and then examine a drop of this water it will bo found to 

 teem with myriads of microscopic creatures, called Iiifu- 

 sorians, because they are found in infusions. The simplest 

 and minutest form of infusnrian is the monad (Fig. 8). 



* See Leidy's Fresli-water Rhizopods of North America, 1879. 



