420 University of Kansas Geological Survey. 



tionships also furnish the basis of classification and are of added 

 interest on that account. 



Morphological difference here, as elsewhere, is merely the ex- 

 pression of differences in physiological activity, the form of the 

 shell registering the growth habit of the organism. In modern 

 methods of classification this fact is recognized, and where 

 formerly distinctions were made upon the plan of growth, now 

 they depend largely upon the results of functional processes. 

 Therefore separation of the order of Foraminifera into the dif- 

 ferent suborders is based upon the character and use of the 

 materials chosen for the shell, and there results, accordingly, 

 the Chitinosa, the Agglutinantia, the Porcellanea, and the 

 Vitro-calcarea. 



Under the Chitinosa are found species that enclose them- 

 selves in a soft chitinous shell and extrude the protoplasm 

 through one or two comparatively large mouth openings. These 

 forms are almost exclusively of fresh-water habit, and because 

 of the character of the shell, are never found fossilized. In the 

 present instance, therefore, little interest attaches to them. 



The suborder Agglutinantia is distinguished from others by 

 the fact that members of it have tests built up from particles of 

 foreign matter fastened together with a cement. These constit- 

 uent fragments are usually silicious in character, but, in the 

 absence of the desired material, minute bits of calcareous or 

 other substances are used. The resulting shells are naturally 

 thicker and rougher than those formed of a homogeneous sub- 

 stance, but otherwise they bear a general resemblance to mem- 

 bers of the other suborders. The geological range is from the 

 Silurian to the present time. 



The Porcellanea are so named because their homogeneous, 

 imperforate, calcareous shells resemble porcelain in reflected 

 light. Protrusion of the sarcode usually occurs through a sim- 

 ple opening, called the oral aperture, or mouth. Range is from 

 the Triassic to the present time. 



The Vitro-calcarea differ from the Porcellanea in having 

 minute perforations in the glassy, transparent shell, through 



