16 ' GENERAL EEMARKS. 



A. Corallum horizontal or obliquely foliate, without proper branches above. 



B. Corallum horizontal or oblique, with erect or ascending branches above, forming 



clumps with concave or convex top — vasiform or cespitose. 



C. Corallum fastigiate ; branches erect, much or closely subdivided ; corallites short and 



round nariform. 



D. Corallum arborescent; branches evenly covered with proliferous branehlets and 



clusters. 



E. Corallum arborescent or fruticose ; branches either not proliferous or unevenly so. 



F. Corallum consisting of a few long stems from a common base, simple or rarely 



branched. 



G. Corallum composed of erect plates in place of proper branches ; no distinct apical 



corallite. 



Milne-Edwards and Hairae divide the genus into two sections — Fasciculatse, with radial 

 corallites, and Distichse, with lateral corallites; only one species is referred to the latter 

 section. The Faseiculatse are divided into five primary divisions, based chiefly, but not 

 entirely, on habit : — 



A. Corallum arborescent; corallites short or moderately prominent, not elongate and 



spiniform. 



B. Corallum arborescent ; corallites tubular and very long. 



C. Corallum cespitose, in the form of rosettes or tufts, rounded above. 



D. Corallum corymbiform or subvasiform. 



E. Corallum foliaceous and little proliferous. 



The divisions A and B correspond roughly, but not exactly, with Dana's divisions E, C, 

 and D respectively. The divisions C and D correspond similarly with Dana's division B ; 

 whilst E is formed by the fusion of divisions A and G of Dana. The plan on which Milne- 

 Edwards and Haime subdivided these main groups is, however, quite different from that of 

 Dana. The form of the radial corallites is rarely employed, but instead the next smaller 

 groupings depend on the condition of the coenenchyma, the degree to which the branches 

 coalesce, the incrusting or pedicellate character of the base, &c. The subdivision need not be 

 followed further for present purposes. 



Klunzinger, in his studies of the Red-Sea Corals, has adopted quite a different classifi- 

 cation of the species of that region, though it is questionable whether he would not have 

 considerably modified his system, had it been necessary to include all the described species. 

 The following table gives the main features of his scheme : — 



A. Axial corallites 4 to 6 mm. diameter. 



a. Aperture of radial corallites central, margin more or less rounded above ; wall 



echinulate or granular, not striate. 



b. Aperture of radial corallites oblique. ' 



