26 PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



but beyond i,6oo feet there is a rapid falling off because the crest of the 

 lithothamnion ridge is laid bare at low tides. 



On the square whose center is 1,650 feet from shore there are 1,512 coral 

 heads, whereas there are 1,838 coral heads on the square whose center is 

 1,425 feet from shore, thus showing that coral heads do not survive so well 

 in the breakers as in somewhat more quiet water. A greater number of 

 species of coral are, however, found in the region of the breakers than any- 

 where else upon the reef-flat, while in the less agitated water nearer shore 



Acrhelia horrescens 



Acropora palifera, etc. 



Acropora hebes. A. pulchra. etc. 



Acropora raurrayensis 



Acropora digitifera 



Astreopora ocellata 



Coeloseris mayeri 



Cyphastrea serailia 



Euphyllia glabrescens 



Favites abdita 



Favites virens 



Favia pallida fac. 3 Vaughan 



Favia pallida fac. 6 Vaughan 



Favia pallida fac- 4 Vaughan 



Fungia fungites 



Goniastrea pectinata 



Goniastrea retiformis "" 



Goniopora tenuidens 



Hydnophora microconos 



Leptastrea purpurea 



Leptoria gracilis 



Maeandra astreiforrais 



Mseandra daedalea 



Montipora aff. informis 



Montipora venosa 



Symphyllia nobilis 



Orbicella curta 



Pavona variant 



Pocillopora bulbosa 



Porites mayeri, P. raurrayensis. etc. 



Porites andrewsi """ 



Psammocora gonagra 



Seriatopora hystrix 



Stylophora pistillata 



Fig. 8. — Diagram showing the range of each species of coral along Line No. I across the southeast 



reef-flat of Maer Island. 



the coral heads are larger and more numerous but the number of species is 

 not so great. Thus, on the square whose center is 1,425 feet from shore, 

 where coral heads are most densely clustered, there are but 18 kinds of coral; 

 whereas in the breakers 1,650 feet from shore there are 26 species of corals, 

 8 being peculiar to this region alone, although the coral heads are here less 

 numerous and are broken by the rushing water. The cause of this may be 

 that in the breakers where the coral heads are small and not densely crowded 

 their struggle for existence is mainly with the sea and not with one another, 



