Vol. 57.] PHYSICAL DEVELOPMENT OF ANTIGUA. 495 



of chert containing well-preserved fragments of silicified wood and 

 freshwater shells. In the lower marine limestones the shells were 

 too poorly preserved for identification, but M. Purves obtained five 

 species of corals ^ suggesting Miocene age ; and some of the corals 

 described by Duncan '^ from the jN'ugent Collection showed that the 

 age is not newer than the older Miocene. Eut Prof. Rupert Jones 

 observed a fragment in the Nugent Collection containing Orhitoides 

 Mantelli^^ which would make the formation from which it came 

 correspond to the Upper Eocene of the American continent. 



In the freshwater cherts i^I. Purves found eight genera^ of 

 gasteropods, all in an excellent state of preservation. Pive of 

 these genera are not found in more recent beds in the island ; and 

 the species of the other three genera cannot be identified with the 

 more modern forms now living on the island. The evidence of the 

 age, derived from these long-extinct forms, supports the antiquity 

 indicated by the corals. 



Collections of fossils from the freshwater beds, which Mr. Forrest 

 found intercalated in the tuffs, were kindly given to me by him, 



Sufiice it here to say that the tufaceous deposits, while older 

 than the succeeding marls resting conformably upon them, had a 

 fauna somewhat different from, though closely related to the latter. 

 Por other information concerning the beds of tuff and their enclosed 

 cherts, M. Purves's work should be consulted. 



^ Prionastraa diversiformis, Mich. Upper Miocene, Bordeaux and Turin. 



Solenastrcsa turonensis, Mich. Miocene, Turin and Touraine. 



Stylocania Ivbato-i'oUmdata (Mich.). Miocene, near Turin, etc. 



Porites Collegnana, Mich., equivalent of incrustans, Ed. & H. Miocene, 

 Turin. 



Alvcopora DcedalcBa, Forskal. Recent, Red Sea, Indian and Pacific Oceans. 

 ^ Astrcsa cellalosa, var. curvata, sp. nov. ; A. megalaxona, sp. nov. ; Solenastrcea 

 turonensis, Mich. ; Isastrcea conferta, sp. nov. ; /. turhinata, sp. nov. ; Stephano- 

 cmiia tenuis, sp. nov. ; Ccaloria dens-elephantis, sp. nov. ; Astroria polygonalis, 

 sp. nov. ; A. affijiis, sp. nov. ; A. antigttensis, sp. nov. ; Astrocoenia ornata, 

 Ed. & H. ; Alveopora Dcedalcea, Blainv., var. regularis & minor ; and later he 

 added Styloc<xnia lohato-rotundata (Mich.), found also in the ]ower limestone 

 of Malta. 



Thus, three species are like European Miocene, nine peculiarly Antiguan 

 species, and Alveopora DcedalxBa is recent. Duncan added three species as 

 coming from the tuff, namely, Stephanocxnia Tenuis, Astrcea cellulosa, and 

 M(gandrina, sp., but M. Purves points out that these come from a liorizon in 

 the tuff above the chert-beds. See Duncan, Quart. Journ. Geol. Soc. vol. xix 

 (1863) p. 411 & Geol. Mag. 1864, p. 97. 



3 Geol. Mag. 1864, p. 102. M. Purves thinks, hovrever, that the specimen 

 containing Orhitoides came from the higher limestone, which would suggest 

 a somewhat earlier Tertiary date for all the deposits. 



^ Bull. Mus. Roy. Hist. Nat. Belg. vol. iii (1884-85) p. 294. The five 

 genera confined to the island are Melania, Zonites, Nemat^tra or Amnicola, 

 Neritina, and Fornatias, and the three genera with species still living are 

 Planorhis, Melampiis, and Truncatella. M. Purves says that Melania proper 

 does not live in the West Indies, but the subgenus Hemisinus occurs in Cuba. 

 Zonites does not occur in the West Indies, though a species was found by 

 M. Purves in Demerara. Neritina is scattered over the i^lands, but not in 

 Antigua. Nematitra is found in the East Indies and in the Oligojene of the 

 Isle of Wight. 



