40 RECENT MADREPORARIA OK THE HAWAIIAN l^^LANDS AND LATSAN. 



Tlir tul.h' shouinu- ill.' I>at h\ i.i.'t lie (list lil. ill ion <>l' tlio genera shows even more 

 clearlv tluiri the disoussion of the species th.> existence of two bathymetric faunal 

 zones": t.ne between u and 25 fathoms; the other, between 1(K» and 4U0. Between 25 

 and 100 fathoms is an intermediate zone; + of til.^ 5 genera between "iS and 40 fathoms 

 represent a downward extension of the shallow water, or leef fauna; 4 of the5oe,uM;i 

 b<>tween 40 and ion fathoms represent the upper limit of the deeper water fauna. 

 The Jun^r/;,,' listed under "40-lOU" fathoms are a " Cydo»erls'' and '' Diaset'is;'' they 

 are not found between other depths around the Hawaiian Islands. 



.Vs th(> region between 100 and 4(>o fathoms represents, in my opinion, one 

 faunal zone, the genera occurring in it are listed collectively, to bring out its richness 

 in genera, and so that it may i>e contrasteel with those found between 1 and 25 fathoms. 



Fhil..Uin,i. CarijophyUiii. Leptmeriis. 



PlaaAvochm. Cijaflioc-rKs. _ Stephanophyllia. 



Gardineria. CeraMnx-lms. ' Endopachys ?. 



■ DcxiuoplnjlJnm. Ardheiii'iphyUla. BidanophyUia. 



Paracyafhus. Madirjiora. Dendrophyllia. 



Deltocyathns. Madracis. Anisopsammia. 



Trochocyatlms. Jfxsm /. 



Of the 20 genera occui-ring in this zone, only 2 were found in the 0-25 fathoms 

 zone. 



This bathymetric zone, limited by the 100 and 400 fathom lines, in the vicinity of 

 the Hawaiian Islands is especially characterized by an abundance of species and 

 genera of Turbinolid and Eupsammid corals and some species of slender, branching 

 Oculinids and Stylophorids. There are also some fragile Fungids. 



The zone between and 25 is characterized by an abundance of larger, more 

 luxuriant corals belonging to the Pocilloporida'. Orbicellida% Faviidic, the simple 

 and compound Fungids, the Montiporina', and the Poritidie. 



Bathymetric studies of this kind are of decided importance in the interpretation 

 of paleontologic data. The following generalizations can be made for the Hawaiian 

 Islands: 



1. An almndance of individuals belonging to the Pocilloporidas, Orbicellida', 

 Faviidie, massive Fungids. Monti porina? and the Poritidie indicate a depth of less 

 than 25 fathoms. Occasional individuals may grow at a depth of 40 fathoms. With 

 increasing depth individuals of the same species become smaller and more fragile. 



2. An abundance of Turbinolid and Eupsammid species, and slender, ramose 

 Oculinids and Stylophorids (as, for instance, Madracis) indicate a depth of 100 to 400 

 fathoms. The best conditions for the growth of these corals are realized between 

 100 and 2(t0 fathoms. 



3. Around the Hawaiian Islands two faunal zones can be distinguished, with an 

 intermediate zone from 25 to 100 fathoms. Within this zone there is some com- 

 mingling of faunas. 



4. Beyond Ihe 400-fathom limit the fauna is poor, and the species outside it are 

 extremely fragile. 



As has been .said, the data at hand warrant these conclusions for the Hawaiian 

 Islands. Many studies of this kind are needed to know more thoroughly the relations 

 between corals and depth of water. 



