The natural limits of the Heliolitidae, 



Having in the preceding section characterized the HeHolitida? I will now review 

 such genera which by some authors have been from time to titne ranked amongst them, 

 stating my arguments foi- not considering them as members of this family of corals. In 

 thns eliminating them from the Heliolitidse I will examine these genera one by one, 

 taking them in alphabetic order. 



Great confusion has arisen because superficia] aualogies or presumed identity of 

 quite different structures have been considered as horaologies. Thus, to give one instance, 

 Bryozoans like Monticulipora, Fistulipora and others, Favositidte and several other corals 

 have been stated to be nearly related to the Heliolitida; or to belong to their family. 

 It is necessary to bear in inind, that these form a well defined and clearly circumscribed 

 group of fossils. Of very little value as a distinction are the tabulaj, these partitions which 

 occur in widel}^ different groups of animals. Cephalopoda, Gastropoda, Conularidte, Annu- 

 lata, Br}'ozoa and Foraminifera share this structure with the Corals. There are, however, 

 slight variations, which make it possible to distinguish between the tabulaä of the Corals 

 and those of the Bryozoa, of which particulars will be given below. . 



Axopora M. Edw. & Haime, H. N. Cor. III p. 243 by them placed amongst their 

 Milleporidas next to Lyellia as occurring in the Eocene formation near Paris and London. 

 It is said th^; the coenenchyma is reticulated and spongy and that the septa are rudi- 

 mentary. In tlEe detailed description of the two principal species again it is said, that 

 there are no septa at all. Some years låter Duncan in Supplem. to Brit. Foss. Corals 

 described two species and these have absolutely no septa. Zittel (Palfeozoologie I p. 288) 

 has placed it amongst the genuine Milleporidaj and this seems to me to be its true affinity. 



Battersbyia M. Edw. & Haime from the Devonian of England, which by these 

 authors was classed as one of the Heliolitidge, has through the researches of Duncan ' 

 been recognized to be one of the Astrceidce, the supposed coenenchyma being only a para- 

 sitic incrusting Stromatopora. Ferd. Roemer ~ again regards it as a Rugose Coral. At 

 all events there is nothing to justify its being ranged with the Heliolitidie. 



Calapoecia Billings (derived from xaÅög, beautiful and dnoixtcc colony, consequently 

 not to be written as Calopoecia or Calapascia as some authors do). Through examination 



* Philos. Transact. vol. 157 p. 648. 

 ^ Letli. palffioz. p. 415. 



