1867.] 



DUNCAN AVEST-INDIAN CORALS. 



9 



tolites found in these rocks. The genera and their distinguishing 

 characters are the following : — 



1 . Dichograpsus, Salter (3 species) : possesses a frond, repeatedly 

 dichotomous from a basal stipe into eight, sixteen, or more branches, 

 each with a single row of cells, the lower part of the stipe being 

 enveloped in a corneous cup. 



2. Tetragrapsus, Salter (3 species) : possesses a frond composed of 

 four simple stipes, arising from a non-celluliferous funicle, which 

 bifurcates at both ends. 



3. PhylJograpsus, Hall (2 species) : differs from the last in pos- 

 sessing a frond composed of four simple stipes united back to back 

 by their solid axes. 



4. Didymograpsus, M'Coy (7 species) : the frond consists of two 

 simple stipes springing from a mucronate radicle, which may be 

 rudimentary or apparently absent. 



5. Diplograpsus, M'Coy (4 species) : two simple stipes, united 

 by their solid axes into a celluliferous frond furnished with a radicle 

 at the base, 



6. Graptolites vel Graptolithus, Linn. (4 species) : consists of a 

 simple stipe, with a single row of cells on one side, and a small, 

 generally curved, radicle at the base. 



7. Pleurograpsus, Nicholson (1 species) : celluliferous branches 

 derived from a main celluliferous rhachis. 



2. On the Fossil Corals (Madreporaria) of the West-Indian Islands. 

 By P.Martin Duncan, M.B. Lond., Sec.G.S. 



Part IV. Conclusion. 



[Plates I. & II.] 



Contents. 



1. Introduction. 



2. Sketch of the Geology of Trinidad. 



3. List of the species of Fossil Corals 



from St. Croix, Trinidad. 



4. Descriptions of the new species from 



Trinidad. 



5. Remarks on the Species. 



6. The Mineralization of the -Speci- 



mens. 



7. Eemarks on the San Domingan Fossil 



Corals : corrections of errors and 

 description of new Species. 



8. Description of some new species 



from Jamaica. 



9. Eemarks on the Antigiian Fossil 

 Corals, and description of new 

 Species. 



10. List of the new Species of West- 



Indian Fossil Corals. 



11. Table of the Synonyms and Lo- 



calities of all the Species of the 

 West-Indian Miocene, Eocene, 

 and Cretaceous Coral-faunas. 



12. Table of the varieties of the Species. 



13. The nature and alliances of the 



Coral-faunas. 



14. Conclusion. 



1. Introduction. — The descriptions of the Fossil Corals of the West- 

 Indian Islands which have appeared in the Society's Journal since 

 1862, appear to have interested many geologists residing in the 

 islands ; and lately the great desideratum, a collection of specimens 

 from the Tertiaries of Trinidad, has been sent to me by the Rev. Mr. 



