i64 CORALS 



long tubes running more or less parallel with one another 

 into the depths of the branches. 



Heteropora has been regarded as the last survivor of 

 a group of fossil Polyzoa called the Treposomata, which 

 occur abundantly in certain Palaeozooic rocks and had 

 some representatives in Jurassic times. It has also been 

 described as a Tabulate coral, but the fact seems to be that 

 in some specimens the tubes are divided into compartments 

 by thin calcareous tabulae and in others they are not. The 

 first of the recent specimens were found in the shallow 

 waters of New^ Zealand, and the genus has more recently been 

 discovered off the coast of South Africa and off the Pacific 

 coast of North America. An examination of specimens from 

 these three localities has show^n that in all general characters 

 they are very similar to one another, and perhaps represent 

 only one widely distributed species which should be called 

 Heteropora pelliculata} But although a few widely separated 

 tabulae were found by the author in specimens from New 

 Zealand, no trace of such structures were found in the 

 South African and Pacific coast specimens. 



Cheilostomata. — In the Cheilostomata the colony 

 usually consists of a number of cubical oval or oblong 

 chambers (the zooecia) provided with a semicircular or 

 crescentic or sometimes circular orifice protected by a 

 chitinous lip or operculum, a second aperture situated just 

 behind the other in some cases, and numerous minute pores 

 arranged in various ways (see Fig. 78). The general effect 

 produced by this structure of the Cheilostomata when a 

 colony is examined with a lens, is to give the impression that 

 it is composed of a large number of closely fitting cells 

 (Fig. 80), and it is this cellular appearance under a low 

 power which mav be taken as the first rough guide to the 

 determination of a coral as a Cheilostomatous Polyzoon. 



The only other coral with which it could possibly be 

 confused might be one of the large Foraminifera such as 

 Gypsina ; but from that it can at once be distinguished 



^ Heteropora magyia, O'Donoghue, from Victoria, B.C., S-i8 fathoms, 

 may be a distinct species, but H. pelliculala also occurs in the same 

 locaHty {Contributions to Canadian Biology, N.S., vol. i., 1923, p. 156). 



