6 Annals of the South African Museum. 



it is exceedingly rare to get knowledge of the growth stages of any 

 one form. But the specimens of C. cenomana here described do not 

 look like proximal ends of zoaria. It is likely, then, that a form 

 exists whose adult zoarium over its greater extent has the characters 

 of I. calypso, d'Orbigny, while these are confined to the proximal 

 parts of an adult zoarium of C. cenomana. 



Distribution of both C. cenomana and I. calypso. Cenomanian. 



CRISINA EXCAVATA (d'Orbigny). 

 Plate I., fig. 6. 



1853. Idmonca excavata, d'Orbigny, Bry. Cret., p. 742, pi. 749, 

 figs. 11-15. 



Zoarium subtriangular with a fiat or concave reverse face ; the 

 lateral series are regular and contain six to eight apertures ; the 

 apertures are circular; the zocecia are emergent. Idmonea filiformis, 

 d'Orbigny (Bry. Cret., 1853, p. 744, pi. 750, figs. 1-5), and Idmonea 

 lata, d'Orbigny (Bry. Cret., 1853, p. 734, pi. 748, figs. 6-10) resemble 

 this form, but have only three apertures in a lateral series. Idmonea 

 marginata, d'Orbigny (Bry. Cret., 1853, p. 744, pi. 749, figs. 20-23), 

 with which Gregory unites this form, differs from it by having 

 immersed zocecia. 



Distribution. Senonian. 



CRISINA MARGINATA (d'Orbigny). 

 Plate I., fig. 7. 



1853. Idmonea marginata, d'Orbigny, Bry. Cr6t., p. 744, pi. 749, 



figs. 20-23. 

 1853. Idmonea angulosa, d'Orbigny, Bry. Crt., p. 735, pi. 748, 



figs. 11-15. 



Zoarium subtriangular with a flat or convex reverse face ; the lateral 

 series are regular and each contains four or five apertures ; the 

 apertures are circular. This form is very like G. excavata (d'Orbigny), 

 but has fewer apertures in a lateral series, and the zocecia are 

 immersed. 



Distribution. Turonian and Senonian. 



GENUS TEEVIA, Jullien. 



Idmoneidse whose zoarium is erect and consists of solid branches. 

 There is an unpaired median series of apertures between the two 

 rows of simple lateral series. Tervia is considered by Gregory as a 



