228 



30 



edges grow thicker and unite without, however, forming a central growth deserving of the 

 name columella. 



As a rule the 6 primary septa are found to be the best developed, but the 6 of the se- 

 condary order are often just as large and can not be distinguished from those of the pri- 

 mary. The remaining septa are small and undeveloped, projecting but slightly from the 

 edge of the calyx. 



The lateral surfaces of the septa are covered with numerous granulations arranged 

 in the usual curved rows. Toward the inner edge of each septum the granulations are larger 

 and those from adjacent septa may touch each other without merging. No dissepiments or 

 other endothecal formations are seen. The intcrseptal compartments are always open in their 

 entirety. 



The stone kernel is very often seen and, on account of the absence of columella, solid 

 and lasting. It is easily recognized by the 48 septal impressions of which every second one 

 penetrates deep into the stone kernel while the alternating one is but slight (table IV, fig. 24). 



Locality: Danien: Younger Danien: Coral chalk at Faxe. Limhamn and Aggersborg- 

 gaard. 



26. Rhizotrochus crassus, Forchhammer and Steenstrup 



Table III. Fig. 4. Table IV. Fig. 25. 

 In the Zoological Museum is a stone kernel with corresponding impressions from the 

 coral chalk at Faxe, which is a great rarity; nothing similar to it is to be found in the col- 

 lection. 



As there is only the single specimen, further investigations by means of cutting and 

 polishing were impossible. 



The stone kernel is 30 mm in length with a diameter at the edge of the calyx of 18 mm. 

 It is obovate-conical in form and regular, though the lower part of the axis is slightly 



bent. 



The stone kernel shows traces of about 60 septa, — 4 complete cycles and the fifth 

 incomplete (6 ordines). The impressions left on the stone kernel by the interseptal com- 

 partments show the same grouping in 4's with deep furrows between as in the species Cera- 

 totrochus ambiguus. There were 12 — 16 larger septa, the others being small. The lateral 

 surfaces of the septa were strongly granular like the inner side of the theca. The interseptal 

 fiUings have therefore a strange prickly appearance characteristic of the species and plainly 

 visible. Table III, fig. 4. 



The impression of the coral in the chalk shows thai it has possessed a thick, smooth 

 cpithecum, forming toward the bottom a large basic disc. The upper part of the epithecum 

 was smooth, the lower part and the basic disc, granular. Table IV, fig. 25. 



There were no dissepiments, and as judging from the lowest section of the stone-kernel 

 there was no columella, it seems justifiable to me to classify the specimen as Rhizotrochus 

 species. 



Locality: Danien: Younger Danien. Coral chalk, Faxe. 



