412 THE AMEBIC AX NATURALIST [Vol.LII 



6-150 ft. depth. Of the 34 Hawaiian genera, 14 habituate 

 this shallow-water zone throughout the archipelago, and 

 10 of these occur on the leeward reefs of Oahu between 

 Leahi and Pearl Harbor. 



Dana's 1 comprehensive statement concerning the reef- 

 building corals may be compactly summarized. He 

 states that it is important to have a correct apprehension 

 of what are those reef species as distinct from those of 

 colder and deeper seas. The coral-reef species of corals 

 are the following: 



1. In the Astrma tribe, all the many known species. 



2. In the Fungia tribe, almost all the known species. 



3. In the Oculina tribe, all of the Orbicelllds; part of the 



Oculimds and Stylasterids ; some of the Caryophyl- 

 lids, Astnoigids, and Stylophorids; all of the Pocillo- 

 porids. 



4. In the Madrepora tribe, all of the Madreporids and 



Poritids; many of the Dendrophyllia family. 



5. Among Alcyonoids, numerous species of the Alryonhim 



and Gorgonia tribes and some of the Penned \dtieea. 



6. Among Hydroids, the Millepores and Heliopores. 



7. Among Alga\ many XuUi pores and Corallines. 

 He further states that 



within LI to Is I ! , , t x , 1 1 | f j ii 

 is never below 74° F. for any month of the year, all the prominent 

 genera of reef -forming species are abundantly represented. The Ha- 

 waiian Islands ... are outside of the torrid zone of oceanic tempera- 



The more abundant reef builders, at moderate depths, 

 are the madrepores, astraeids, porites and meandrines. 

 At depths of 90-120 ft. the millepores and seriatopores 

 predominate. The great field of coral development thus 

 lies between low water and 120 ft. 



Dana's classification of reef-formations is useful in sur- 

 veying the Hawaiian reefs: 



i James D. Dana, "Corals and Coral Islands," 1872. 



