160 MADREPORARITA. 
are much divided and bear numerous spreading twigs and short proliferations. In specimens 
which extend obliquely the marginal branches closely resemble those of the cespitose form, 
but the central ones are suberect, arcuate, distinctly tapering, and not so proliferous. Axial 
corallites 3 to 4 mm. diameter (but not so stout on the smaller twigs), short cylindrical, 
margin often a little rounded. Radial corallites much crowded, irregular, chiefly half-tubular 
or short-labellate, with rounded or plane apex, sometimes distinctly compressed ; in some 
specimens the form is more nearly nariform, or, if the inner part of the wall is at all 
prominent, tubo-nariform, but in most specimens the inner part of the wall is not developed ; 
diameter usually 15 mm., more rarely 2 mm., with a few immersed cells scattered between. 
The corallites usually remain more or less prominent quite to the base of the branches unless 
on the under surface of oblique specimens. Star very prominent, but sometimes consists of 
only 6 septa. Wall moderately thin and porous in the majority of cases, but the outer 
part is distinctly thickened in the stouter corallites. Corallum porous; surface spongy- 
reticulate and echinulate ; wall striato-reticulate when thin, striate and echinulate if thicker. 
Var. pustulifera. (Plate XX VII. fig. B.) 
Madrepora pustulosa, Briiggemann (non M.-Edwards & Haime), Phil. Trans. 1879, vol. clxvill. p. 574. 
A variety which exhibits the same variations in habit as the type, and differs chiefly in 
the form of the radial corallites, the majority of which are tubular with a somewhat oblique 
aperture ; wall thin and striate as in the type. 
Indo-Pacific Ocean; Torres Straits and Great-Barrier Reef area, Rodriguez. 
a-c. Thursday Island. Saville-Kent Coll. 92. 6. 8. 248 to 250. 
d. Warrior Island. Saville-Kent Coll. 92. 6. 8. 252. 
e. Palm Island. Saville-Kent Coll. 92. 6. 8. 2538. 
jf-h. Low-Woody Island. Saville-Kent Coll. 92. 6. 8. 254 to 256. 
i. Rocky Island. Saville-Kent Coll. 92. 6. 8. 257. 
Var. pustulifera. 
a-f. Rodriguez. Royal Society [P.]. 76.5. 5.94 to 98 & 
100. (= M. pustulosa, Brigg.) 
g. Thursday Island. Saville-Kent Coll. 92. 6. 8. 251. 
Division ITI. 
7. Subgenus CONOCYATHUS. gx+ hue 
Corallum corymbose, cespitose, bushy, subarborescent or reticulate, differing chiefly from 
Tylopora in having more slender apices to the branches and relatively small conical axial 
corallites with rounded apex. The prominent radial corallites have a dense wall with the 
margin rounded. The M. variabilis group shows an approach to M. brueggemanni var. 
uncinata in the form of the radial corallites, but not in habit. The M. polymorpha group 
leads to the form characteristic of M. rosaria and its allies. 
