98 MADEEPORAEIA. 



The following is a description of the specimen in the Paris Museum, which is regarded as 

 Lamarck's type : — 



Corallum openly vasiform and pedicellate, 29 cm. diameter, and 11 cm. high. The 

 branches of which the vase is composed have a length up to 15 cm., and are 1 cm. diameter 

 near the base ; the branches are crowded, with long narrow spaces between, but fusions are 

 numerous to near the margin of the vase. There are numerous immersed and subimmersed 

 corallites on the under surface, and also a large number of wart-like buds, which consist of a 

 central tubercle about 35 mm. long and 3 mm. diameter, with a few subimmersed corallites 

 around. These bud-branches are mostly at right angles to the under surface, but a few 

 which are lateral become branched, pressed into the general plane, and may attain a length 

 of 1'5 cm. The superior surface of the main branches is clothed with immersed or short 

 iabellate corallites. Innumerable short branchlets arise from this surface, having a maximum 

 length of 2 cm., and 6 or 7 mm. diameter at the base; they are rapidly tapering, arched so 

 as to reach the same level, mostly proliferous, but a few are simple. Axial corallites 1*5 

 mm. long and broad, wall firm. Radial corallites half-tubular or Iabellate at an angle of 

 about 45°, a little over 2,mm. long and over 1 mm. thick, very fragile, becoming rapidly 

 shorter below the proliferous apices. Septa of the axial corallites moderately developed, a 

 second cycle sometimes recognizable ; in the radial Iabellate and immersed corallites the 

 directives are very narrow and the others rudimentary. Corallum fragile and very porous 

 in section ; surface strongly echinulate and reticulate, but firmer on the main branches ; wall 

 strongly ribbed and echinulate, reticulate between. 



This species is extremely variable, both in habit and in the character of the corallites, 

 and many specimens which are referable to it differ in a marked degree from the type 

 specimen. The axial corallites are cylindrical, usually 2 or occasionally 3 mm. broad and 2 

 to 3 mm. long, with the wall a little thickened ; the size varies considerably in different 

 specimens. Radial corallites half-tubular, dimidiate or spathulate, 1 to 2 mm. broad and 

 2 to 3 mm. long, more spreading and crowded near the apex ; immersed at the base of the 

 branchlets and on the stouter parts. The under surface in the subcomplanate forms always 

 bears numerous short twigs and elongate tubular corallites up to 4 or 5 mm. in length. The 

 form of the colony is either : — 



a. Vasiform or subvasiform. (Var. vasiformis.) 



b. Hemispherical or bushy, with slender elongate middle branches and short, much divided 



marginal ones. (Var. hemisphmrica, Ehrb.) 



c. Broad corymbose, convex on the upper surface, with the branchlets and corallites as in 



form d; compare Klunzinger's pi. ix. fig. 16. (Var. corymbiformis.) 



d. Cespito-tabulate, with the main branches extending horizontally, and the branchlets 



short and stout. (Var. emspito-tabulata, Klz.) 



e. Incrusting, without or with much depressed branchlets, as in M. seriata, var. depressa. 



(Var. depressa, Klz.) 



Klunzinger observes that some specimens of the cespito-tabulate form are similar to 

 M. cytherea, Dana, but may usually be distinguished by the less pointed corallites, the less 

 developed branches, and the less naked under sui'face. In other cases, however, it is 

 extremely difficult to separate the two forms, ioA ultimately it may be necessary to regard 

 both as varieties of one species. 



