ZONATULA. 
213 
typical form, or in horizontal constrictions (var. annulata^)^ 
or are somewhat irregular in distribution (var. irregularis ^). 
DIME^’■SIO^’S. 
Ahn Hagenow’s type. B.M. specimens. 
Height of zoarium 
Diameter of branches ... ... 5 
Width of a node from constriction 
to constriction .. . ... ... 3 -5 
(average of six) 
Diameter of apertures .. ... •! 
Diameter of mesopores -033 
Largest specimen is tO mm. 
high X 41 mm. wide. 
3-10 mm. ; average 5 mm. 
One specimen at base is 
12 mm. 
•14 mm. (D. 3468). 
Figures. 
PI. VII. Fig. 4<?. A zoarium from the side ; X 2 dia. Fig. 
the upper surface of the same specimen, showing a transverse 
section of the main stem and oblique section across base of a branch ; 
X3dia. Maastrichter Kalk : Maastricht. Van Breda Coll. D. 3366 . 
Fig. 55.— D. 3468. 
Fig. 56.— D. 3469. 
Zonatula pseudotorquata, var. irregularis. Vertical sections ; x 18. 
PL VII. Fig. ba. A thick zoarium of var. annulata from the 
side ; nat. size. Fig. bh, part of the surface of the same specimen ; 
X 6 dia. Maastrichter Kalk : Maastricht. Van Breda Coll. 60 , 164 . 
These varietal names are new. 
