AMONU SIMPLE SAUCODK OUUANISMS. 297 



investment, in which is immersed an immense number of tangen- 

 tially or irregularly disposed, curved siliceous spicula, and through 

 vi'hich the pseudopodia pass from the surface of the inner sphere 

 to the surrounding water. The species oiltapliidiopJirys, however, 

 are usually found in the condition of colonies. One of these colony- 

 forming species, JR. elegans (fig. 15), has been described and figured 

 by Hertwig and Lesser as a cluster of globes united rather loosely 

 to one another by thin bridges of protoplasm, across which the 

 sarcode currents may be seen passing from one globe to the other, 

 while the whole cluster is surrounded by the common soft invest- 

 ment in which the spicula are immersed, and which allows the 

 passage across it of the long fine pseudopodia from the periphery 

 of the included globes. 



-5. viridis, one of tlie finest of all the freshwater Ehizopoda, is 

 described by Archer*, who has taken it as the type of the genus. 

 It is also a colony-forming species, and is distinguished by its 

 bright green colour, causei by a dense stratum of chlorophyll gra- 

 nules which lie just within the periphery of each of its component 

 spheres. 



Under the name of Pinacocystis ruhicunda (fig. 16), Hertwig and 

 Lesser have described an interesting skeleton-bearing heliozoan 

 which they found in sea-water. Its spherical body is surrounded 

 by a case which consists of isolated round tablets lying close to 

 one another, and thus forming a completely closed capsule. They 

 compare this capsular skeleton to that of an Acanthocystis, in 

 which the whole of the spines, with the exception of their basal 

 plates, had disappeared. 



The protoplasm body is separated from the capsule- walls by an 

 interval which would seem to correspond to the similar interval 

 between the body and the basal plates of the spines in Acanthocystis. 

 The protoplasm shows a very decided differentiation of ectosarc 

 and endosar<3. The ectosarc is loaded with brownish-red granules ; 

 and the endosarc contains a single nucleus. Contractile vacuoles 

 could not be demonstrated. The pseudopodia are emitted through 

 the intervals of the capsule-tablets. 



A closely allied form is that of Pinaciophora JIuvicUilis, Greeft". 

 This heliozoan was found by Grreeff in freshwater streams. It 

 resembles Pinacocystis, Hert. & Les., in being surrounded by a 

 globular capsule composed of separate though closely approxi- 

 mated plates, but difters from it in the oval form of these plates. 

 * Quart. Jourii. Micr. Sci. vol. xi. 1871. 



