PROM THE ZONE OF AMMONITES ANGULATUS. 



•27 



ornamented 



The surface of the 



coenenchyma \ '^^'^S^^ 



plain 



rudimentary 



AstrociBnia insignis. 



— svperLa. 



— costata. 



— (jihbosa. 



— gibbosa. 



— plana. 



— minuta. 



— reptans. 



— dendroideu. 



— parasitica . 



— pedunculuta. 



— favoidea. 



Genus nov. — Cyathoc(enia. 



This genus has been determined for species which, had they columellse, would belong 

 to the genus Astroccenia. 



The walls of the corallites of the species are joined, and there is more or less coenen- 

 chyma. The costae are not confluent, and the septa are finely dentate. There are 

 no pali, nor is there a columella. There is no fissiparity, and the gemmation is either from 

 the intercalicular surface, or from the calicular margins. 



There is always some coenenchyma present, and this distinguishes the new genus from 

 Isastraa, the only genus with which it can be confounded. 



The following is the generic formula : 



Cyathocoenia. — The coralluni is compound. The corallites are united by their walls 

 and by more or less coenenchyma ; they are more or less polygonal, but are often cylin- 

 (drical. The calices are small, the costae are not confluent, and the septa are finely 

 dentate. There is no columella. There mi no structures on the coenenchyma between 

 the calices except granules and costae. The gemmation is superior and marginal. 



1. Cyathoccenia DENDRoiDEA, Buncan. Plate IX, figs. 6, 7, 8, 9. 



The corallum is large and tall, forming fasciculate masses. The corallites are more or 

 less crowded on the surface of stems, which branch rarely, and which are close and more 

 or less parallel. The transverse outline of the stems is irregular, from variability in 

 their thickness, and also from the presence of superficial calices. The stems consist of 

 calices separated by coenenchyma whose amount varies. 



The calices are distant when there is much coenenchyma, but occasionally they are 

 close, and their margin then becomes round ; they are small, are irregularly placed, and 

 are rather deep. 



