B ZOOLOGY SECT. 



elicate ; in the number of nuclei ; and in the presence or absence 

 f a hard shell within or around the protoplasm. The following 

 3ur orders may be distinguished : — 



Order 1. — Lobosa. 

 Rhizopoda with short, blunt pseudopods. 



Order 2. — FoUamiinifera. 



Shelled Rhizopoda with fine, branched, and anastomosing 

 iseudopods. 



Order 3.— Heliozoa. 

 Rhizopoda with fine, stiff, radiating pseudopods, 



Order 4. — Radiolaria. 



Rhizopoda having a shell in the form of a perforated central 

 apsule, and usually, in addition, a siliceous skeleton : the pseudo- 

 lods are long and delicate. 



Systejnatic Position of the EMdrvpk. 



Amoeba proteus is one of many species of the genus Amceba, 

 jclonging to the family Ammbidm, of the order Lobosa. The blunt 

 jseudopods not uniting to form networks place it among the 

 Liobosa : the absence of a shell, among the Amoebidse. The genus 

 Amoeba is distinguished by the presence of one or more nuclei, 

 i,nd of a contractile vacuole. In A. proteus the pseudopods are 

 )f considerable length and sometimes branched, and there is a 

 lingle nucleus, having its chromatin in the form of scattered 

 granules. 



Order 1. ^Lobosa. 



G-eneral Structure. — The members of this group all agree 

 ,vith Amoeba in essential respects, their most characteristic feature 

 Deing the short, blunt pseudopods. The chief variations in struc- 

 ture upon which the genera and species are founded have' to do 

 ,vith the number and character of the nuclei, the form of the 

 )seudopods, and the presence or absence of a shell. 



In AmcBba itself there may be one (Fig. 30, E) or several (b) 

 nuclei, the chromatin of the nucleus may be arranged in various 

 A'ays (f, h), and the pseudopods may be prolongations of con- 



