Rehitionships of the Rugosa to (he living Zoantheip. 381 



reach beyond the fourth and never attains the anal cell ; it is 

 straight on both its borders. 



Length 8^ miliim. 



One of the specimens from Borneo does not measure more 

 than 6^ millira. 



[To be continued.] 



LXIII. — Relationships of the Rugosa {Tetracoralla) to the 

 living Zoanthece. By J. E. DUERDEN *. 



"When briefly discussing, in 1871, the Palaeozoic corals in- 

 cluded under Milne-Edwards and Haime's order Rusjosa, the 

 late Count Pourtales thus remarks: — "Mr. R. Ludwig has 

 shown (H. V. Meyer's ' Pala?ontograpliica,' vols. x. and xiv.) 

 that the tetraineral arrangement claimed for the Rugosa is 

 only apparent, there being originally six primary septa, but 

 that further development in each system is asymmetrical, and 

 that two of the systems remain generally undeveloped. [ 

 had, before having knowledge of Ludwig's researches, come 

 substantially to tlie same conclusions by the examination of 

 Lophophyllum proJiftrum, Edw. & H., from the Carboniferous 

 formation, a form very suitable for that study. . . . When 

 the youngest stage of the coral is examined by cutting through 

 the tip of the conical LophophyUum proliferum^ six primary 

 septa and six interseptal chambers are found, placed sym- 

 metrically on two sides of a vertical plane, and unequally 

 developed." 



'J'he very elaborate and painstaking researches of LudA'ig 

 and the above definite statement of Pourtalfes have appa- 

 rently never been accorded the full consideration they deserve 

 in any discussion of the aflSnities of tiie Rugosa. Supported 

 by the conclusions of Kunth (1869), it seems to have been 

 generally accepted by most students of this extinct group of 

 corals that the adult arrangement of the septa around four 

 principal members is sufficient evidence for assuming a 

 primary tetrameral plan. The procedure is in some measure 

 to be accounted tor by the rarity with which the earlier stages 

 in the growth of the septa of fossil corals are procured, and 

 the difficulties involved in their investigation. 



Tetramerism, both primary and secondary, has been the 

 conception underlying most of the receut attempts which have 



* From the 'Johns Hopkins University Circulars,' vol. xxi. No. loo, 

 pp. 19-25 (Jan. 1902). 



