CORALS AISTD CORAL REEFS VAUGHAN. 221 



species in Wood Jones's collection from Cocos-Keeling Islands, but 

 it is known that a few more species occur in the latter group of is- 

 lands. I collected at the Tortugas, Florida, about 32 species, but this 

 does not represent all the species in the Floridian reef fauna, and 

 about 26 species at Cocoanut Point, Andros Island, Bahamas, but ad- 

 ditional species were collected on the reefs near the mouth of South 

 Bight, and other species are known to occur in the Bahamas. The 

 total number of Bahamian shoal-water species is about 35. There- 

 fore, on a segment of a rich reef in the Indo-Pacific there are about 

 twice as many, or a few more than twice as many, species as there are 

 on a similar segment of a West Indian or Floridian reef. It would 

 require too much space to discuss the systematic differences between 

 Indo-Pacific and Atlantic faunas here, but it may be stated that the 

 following are the names of some of the Indo-Pacific genera not 

 known living in the Atlantic, viz : Poclllojiora* ^ Seriatopora^ Stylo- 

 phora*^ Euphyllia*^ Cyphastrea^ Leptastrea^ Galaxea*^ AntiUea*, 

 Favites*, Trackyphyllia, Hydiwphora*, Leptot'^ia*, Symphyllia, Fun- 

 gia, Herpetolitha^ Polypkyllia^ Halomitra^ Podohacia^ PaehyseHs^ 

 Pavona*, Leptoso^* , Hcdoseris*, Coeloseris^ Psarmrwcora^ Diploas- 

 trear^ Astreopora*^ Turbinaria, Montipora., and Goniopora* ^ but 

 those whose names are marked by an asterisk (*) occur in geologic 

 formations of Oligocene age in the southern United States, the West 

 Indies, and Central America, and some of them range upward into 

 the Miocene. This list might be greatly increased, but it will impress 

 the reader that many genera now living in the Indo-Pacific region, 

 but absent in the living Atlantic fauna, are represented in the Ter- 

 tiary geologic formations on the Atlantic side of the North American 

 Continent. Of the Atlantic genera not known to be living in the 

 Indo-Pacific region there are Stephmiocoema, Eu^m'dia^ 3Iea(ndrina, 

 Dendrogyra, and Mamelna, and some other genera are probably not 

 represented there, while the species of other genera that are repre- 

 sented in both the Atlantic and the Indo-Pacific are not closely 

 related. 



That the Indo-Pacific and Atlantic faunas were not always so 

 distinct as they now are has been indicated in the foregoing para- 

 graph. Geologic investigations have revealed that during later 

 Eocene, all or most of Oligocene, and a part of early Miocene time, the 

 two oceans w^ere connected across Central America, and that the 

 same faunas occurred in both oceans. In places the older Tertiary 

 faunas in the West Indies contained as many species as are at present 

 found on an Indo-Pacific reef. For instance, about 69 species are 

 reported from the Oligocene of the island of Antigua, where I per- 

 sonally collected 60 species. In middle and later Miocene time the 

 Atlantic and Pacific became separated by a land bridge from South 



