II 



PHYLUM PROTOZOA 



53 



increase in the number of chambers there is a multiplication of 

 the nucleus (Fig. 34, 4, b, nu). 



The shell presents two leading types of structure, apart from 



tSoccammina 



2.Lagena 



3-Nodosaria 



4.Frondicularia G.GIobigerina 



7. Discorbina 



9.Planorbulina 



ll.Nummulites 



FIG. 35. Shells of Foraminifera. In 3, 4, and 5, a shows the surface view, and b a section ; 

 Sa is a diagram of a coiled cell without supplemental skeleton ; Sb of a similar form 

 with supplemental skeleton (s. sJ-.) ; and 10 of a form with overlapping whorls ; in lid half 

 the shell is shown in horizontal section ; b is a vertical section ; a. aperture of shell ; 1 15, 

 successive chambers, 1 being always the oldest or initial chamber. (After Carpenter, Brady, 

 and Butschli.) 



the form and arrangement of the chambers : either it is of a 

 porcelain-like texture and provided with a single terminal aperture, 

 (Fig. 34, 4), or the texture is glassy and the whole shell perforated 



