INTRODUCTION. xxix 



23. Genus Plerogyra. 



Milne Edw. and J. Haime, loc. cit., p. 284, 1848. 



Corallum composed of long, thick, slightly ramified gyri, united laterally by their lower 

 part, and free only near the calicular margin. No columella. Septa exsert, and broad ; 

 interseptal loculi very broad, and almost entirely filled up with large vesicular dissepiments, 

 constituting a cellular mass. Walls presenting some costal striae near the calicular margin, 

 but covered in all the other parts by a vesicular structure, which becomes highly developed 

 between the gyri. 



Typ. sp., Plerogyra laxa, Milne Edw. and J. Haime, loc. cit., tab. vi, fig. 8. 



Section III.— EUSMILINtE AGGREGATE. 



Corallum composite and massive, in which the corallites are not arranged in series, 

 and although remaining quite distinct, are united together by their walls, by a costal 

 coenenchyma, or by mural annular expansions. 



This group corresponds to the division of the Astreince aggregates of the second tribe of 

 this family, and constitutes with these the great genus Astrea of most authors. 



24. Genus Stylina. 



Lamarck, Hist, des Anim. sans Vert., t. ii, p. 220, 1816 ; Fascicularia, Lamarck, Extrait du Cours, 1812. 



Corallum glomerate, astreiform. Corallites very tall, united by means of the costal 

 system and its dissepiments, and having the appearance of small truncate cones at their 

 upper end. Calices circular, with their margin free; usually distant from each other. 

 Columella styliform and projecting. Septa exsert, arched at their apex ; in general not 

 numerous, and forming as usual six systems. No pali. Walls thick. 



Typ. sp., Stylina echinulata, Lamarck, loc. cit. ; Milne Edw., Atlas du Regne Animal de Cuvier, 

 Zooph., pi. lxxxv, fig. 3. 



25. Genus Styloccenia. 



Milne Edw. and J. Haime, An. des Sc. Nat., 3 me sene, t. x, p. 298, 1848. 



Corallum having the form of a very thick sheet, convex or bent in different ways ; 

 covered inferiorly by a finely-striated epitheca; and increasing by marginal gemmation. 

 Corallites united by their walls, which are thin and prismatic. Calices polygonal, then 

 margins simple, and bearing at their angles small, columnar, grooved processes. Columella 

 styliform, projecting. Septa very thin, not exsert, nor numerous, and forming six systems. 



Typ. sp., Styloccenia emarciata, Milne Edw. and J. Haime, loc. cit., tab. vii, fig. 2; Astrea emarciata, 

 Lamarck, op. cit., t. ii, p. 266. 



