12 RHIZOPODA. 



Order II. STIGHOSTEGIA. 



Dentalina (D'Orbigny). Animal free in the 

 shell; shell regular, equal-sided, slightly bowed, 

 with a single central round orifice. 



D. recta. Fig. 11 ; f 

 ? subarenata. 



Order III. HELICOSTEGIA. 



Nonionina (D'Orb.). Shell equal-sided, spire 

 rolled in the same plane; orifice single, against 

 the return of the spire, always visible. 



N". crassula. Fig. 12 ; mag. 



Polystomella (Lamk.). Orifices numerous, on 

 the last chamber, and on the sides of the shell ; 

 chambers simple, furnished with one sole cavity. 



P. crispa. Fig. 14 ; 2 T . P. crenatula. 

 Gulielininse. nautilina. 



Rotalina (D'Orb.). Shell unequal-sided, spire 

 rolled obliquely, and completely formed; orifice 

 simple, crescent-shaped, on the last chamber only, 

 on the middle of its breadth. 



E. Beccarii. Fig. 13 ; 2 T 5 . 



Globigerina (D'Orb.). As Rotalina, but the 

 orifice is at the umbilical angle. 



G. inflata. Fig. 15 ; mag. 



Truncatulina (D'Orb.). As Rotalina, but the 

 orifice is a slit continued from one chamber to 

 another, on the spiral side. 



T. lobatula. Fig. 20 ; mag. 



