ÖFVERSIGT AP K. VETENSK.-AKAD. FÖRHANDLINGAR 1900, N:0 1. 9 



lamellfe is so characteristic in other Corals. These spines remind 

 of the synapticulffi of tlie Fungidte thougli lacking in the regular- 

 ity in arrangement and the compactness which characterize this 

 class of dissepiments. 



This new species may be suitably named Thecoct/athus 

 Natliorsti after the arduous explorer of Arctic regions. That it 

 really belongs to this genus is best deraonstrated tlirough a 

 comparison with other species of this genus. If we at first inspect 

 the common, well preserved Liassic Thec. mactra' Goldf., we 

 see that also there no true pali exist, but on the contrary the 

 septa are divided in several free Standing papillse, which continue 

 to the central axis of the coral in the sarae direction as the 

 septa and in continuation of theni. Tf, as generally has been 

 the opinion, these detached papillae were to be regarded as paluli 

 there had in this coral beeil many irregulär rows of paluli. But 

 they cannot any raore than in Thec. Nathorsti be considered as 

 paluli, only as detached parts of septa. These central papillas 

 give a semblance to a columella where they are crowded. They 

 are, however, as in Thecoc. Nathorsti arranged radially and are 

 more numerous in consequence of the greater nuraber of septa 

 in Thec. mactra. The same sort of union between septa of a 

 third order with those of the second prevails also here, as well 

 as in the other Liassic species Thecoc. Moorei. i) It is to be 

 borne in mind that many of the figures given in palceontological 

 works, as those of the common Thecoc. mactra, by no means 

 are as accurate as desirable. In several figures of these corals 

 the details have been adjusted so as to answer to the generic 

 characters or to the specific descriptions, as may be seen when 

 comparing speciraens with figui'es said to be copied from them. 



But the species which is most allied with the Thecocyathus 

 Nathorsti is the miocene Th. velatus Reuss. '^) The whole 

 aspect of the calicle is in the highest degree identical. There are 



') Edw. & Haime. British Fossil Corals, p. 144. 



^) Die fossilen Korallen des oesterreich-ungarisclien Miocäns. Denkschriften d. 

 K. K. Ak. Wiss. Wien 1872, p. 219, Taf. II f. 5—7. 



