EHIZOPODA. 21 



ricjlit ano-les to the centre of the disk. Each of 

 the seofments of sarcode contained in these oblonor 

 chambers communicates by means of a double 

 footstalk with a pair of circular stolons, a con- 

 centric series of which lie beneath both the 

 upper and lower surfaces of the shell. These two 

 sets of stolons are connected with one another by 

 means of linear bands of sarcode, enclosed in 

 columnar chambers which run through the inter- 

 mediate thickness of the disk. Each of these 

 linear bands sends forth a double series of sarcode 

 threads, which serve to bring it into connection 

 mth a pair of the columns belonging to the zone 

 on its interior, those of the outermost zone having 

 probably the power of protruding pseudopodia 

 through the numerous rows of marginal apertures. 

 The texture of the shell is also deserving of 

 notice. In Gvomia and a few other forms it is 

 somewhat membranous, whilst in Proteonina it is 

 arenaceous. These, however, are exceptional in- 

 stances, since in the greater number of Foramiinl- 

 fera the shell is eminently calcareous, presenting 

 various degrees of consistence. In Lagena it is 

 hyaline, but in Miliolina and its allies it becomes 

 unusually opaque, so as nearly to resemble white 

 porcelain. In newly formed segments, the shell 

 is usually deficient in thickness. 



TO. Tee^ss^leal Terms. — For the better de- 

 scription of the multilocular Rhizopods certain 

 technical terms have been proposed. Thus the 

 several chambers of which the shell consists have 

 received the name of segments, that from which 

 all the others originate by a process of gemma- 

 tion being known as the primordial, whilst that 



c 3 



