Vol. 51.] AND PHYSICAL GEOLOGY OF THE WEST INDIES. 275 



Endotheca scanty. Coenenchyma thinner than in other species of 

 the genus. Echinulation of the surface coarse. Epitheca thick and 

 well developed. 



Dimensions. Diameter of an average corallite, 3 mm. ; height of 

 corallite varies from 10 to 25 mm. ; thickness of wall varies from 

 1| to 3 mm. 



Distribution. Recent: West Indies. Fossil: Barbados: Low- 

 level Reefs, near Bridgetown (Franks Coll.). 



Figures. PL XL fig. 2 a, the coral reduced to 5 ; fig. 2 b. corallites 

 from the surface of a flat area ; fig. 2 c, corallites on a boss on the 

 same specimen (B.M. R 2514) ; fig. 3, section of a corallite, enlarged 

 from another specimen (B.M. R 2513). 



Affinities. This species is most closely allied to Echinopora rosu- 

 laria, Lamk., of which a good figure has been given by Blainville 

 (' Man. Act.' pi. lvi. fig. 2). The old species may, however, be easily 

 distinguished by the greater irregularity in the distribution of the 

 corallites, which are much farther apart. E. aspera (Ell. & Sol.) 

 agrees in the general form, but differs by the great development of 

 spines and denticles on the upper surface ; the thinness of the 

 branches, and the rudimentary character of the epitheca, also 

 separate the species. E. Ehrenbergi, M.-Ed. & H., 1 sometimes 

 approaches E. Franksi in the thickness of the expanding lobes, 

 but these never attain the strength of the West Indian species ; 

 the coenenchyma in the latter is, moreover, radially echinulate and 

 not irregularly spinous. 



This species is, in fact, exceptionally well marked off from those 

 species of which adequate illustrations and descriptions have been 

 given. The genus, moreover, has not been previously definitely 

 recorded from the West Indies. Lamarck 2 described a species, 

 E. ringens, of which he says ' je la crois des mers d'Amerique.' Dana 

 (' Zoophytes,' p. 279) has quoted Lamarck's diagnosis, and puts it as 

 ' West Indies ? ' Two points in this scanty diagnosis suggested at 

 first that the Barbados specimens really belong to this species : these 

 are the general form of the coral and the closeness of the corallites. 

 The former character is, however, of little value ; and doubt is 

 thrown on the last by the corallites being also described as sub- 

 confluent and sinuous. In this species they certainly are not, and 

 this is really the only definite character in Lamarck's diagnosis. 

 The corallites, moreover, instead of being irregular, are more regular 

 than in most species of the genus. It would therefore be unwise to 

 resuscitate Lamarck's practically unrecognized name. I have much 

 pleasure in naming the species after Mr. G. F. Franks, by whose 

 energy in forming a collection of recent and fossil species from 

 Barbados it has been possible to work out the relations of the two 

 faunas. 



1 Ann. Sci. Nat. Zool. ser. 3, t. xii. (1850) p. 187. 

 - 'Hist. Nat.' 1816, vol. ii. p. 256. 



