1853,] LONSDALE — SAN DOMINGO FOSSIL CORALS. 133 



by Mr. Heneken from the " Drift " of the Nivaje district, and from 

 "the silt of the sandstone plains;" but neither of them has been 

 examined further than was necessary to ascertain whether they in- 

 clude any species identical with those obtained directly from the 

 regular deposits. In three instances approximate agreements have 

 been detected. One of them is a Placocyathiis ? found in the Nivaje 

 deposit, and its presumed analogue was derived from " the silt of the 

 sandstone plains," which appears, from information kindly afforded by 

 Mr. Heneken, to have chiefly resulted from denudated tertiary strata. 

 The two other instances are a species of Dichocoenia, and a fossil 

 seemingly allied to the Mussce gyrosce. They both belong to the 

 " tufaceous limestone," and the supposed representative of the Dicho- 

 coenia was procured from the " silt ; " but the coral provisionally 

 referred to Mussa was discovered in the "drift" of Cerro Gordo. 

 In these cases, however, the information yet obtained is insufficient 

 to establish a specific identity ; and, as respects the " drift " specimen, 

 doubts are entertained if it had been previously derived from the 

 limestone deposit. 



It may be added, that the corals of the " drift " are, as a whole, 

 distinct from those of the " silt of the sandstone plain," and, so far 

 as the evidence extends, they bear more the semblance of the existing 

 tKan of a tertiary fauna. 



T4ie fossils believed to be referable to the Nivaje shale belong to 

 ten species, and are assigned absolutely or provisionally to the follow- 

 ing genera, according to the recent classification of M. Milne-Edwards 

 and M. Jules Haime : — 



1. Placocyathus ?, 2 sp. 6. Astrsea, 1 sp. 



2. Ceratotrochus ?, 1 sp. 7. Pocillopora, 1 sp. 



3. Flabellum, 1 sp. 8. Undescribed genus referable to the 



4. Rhipidogyra ?, 1 sp. Subfamily Eupsamminse, 1 sp. 



5. Circophyllia, 2 sp. 



Of the seven named genera, six are stated in the ' Archives du 

 Museum d'Histoire Naturelle' (t.v.) to have tertiary representatives, 

 namely Ceratotrochus, one eocene and three miocene species * ; Fla- 

 bellum, six 1 eocene, eleven 1 miocene, and four pliocene, besides three 

 with no fixed tertiary epoch ; Rhijndogyra and Pocillopora have one 

 miocene species each, and Circophyllia one eocene, and AstrcBa nine 

 miocene. Descriptions of the whole of these corals, except one un- 

 certain generic determination, have been carefully consulted, but not 

 a single identification with a Nivaje fossil could be established. 



It may be not altogether useless to state, that, of the seven genera 

 above mentioned, three — Ceratotrochus, Rhipidogyra'\, and Circo- 

 phyllia — do not appear to have yet been obtained in a living state ; 

 while the locality, whence the only described existing species of Pla- 

 cocyathus was procured, is unknown ; the recent species oi Flabellum 

 are confined chiefly to the Indian Ocean and Chinese seas, and Pocil- 

 lopora is stated by Mr. Dana to occur solely among coral-reef-areas ; 



* The genus of the eocene fossil is given doubtfully, and one of the miocene 

 species is stated to occur also in a pliocene deposit, 

 t As limited in the ' Archives,' t. v. p. 57. 



