52 MADREPORARIA. 
small labellate or subimmersed ones occur. The cylindrical corallites are not developed on 
the under surface of the main divisions, and on the upper surface there is usually not such a 
marked difference between the two types of corallite ; the more prominent ones have the inner 
part of the wall more or less incomplete and those between are chiefly immersed. Star 
usually not recognizable, even in the stouter corallites, and when present is situated deep down 
in the cup, so that it is scarcely seen from above, often easiest to make out in the immersed 
corallites on the stouter divisions. Corallum dense ; surface reticulate and echinulate ; wall 
deeply and closely striate (rugose), echinulate at the base. 
One specimen from the same locality as those belonging to form @ has the same habit 
and similar stout ascending branchlets, but the corallites are short and subequal with a few 
immersed or labellate ones between, so that the divisions have a neat terete appearance. 
Specimens from Thursday Island resemble those from Rocky Island Reef (form a) in habit, 
but the radial corallites are rarely so stout and have a more oblique aperture. 
Form 4.—Corallum fruticose from an incrusting base; colony about 20 cm. high and 
28 cm. wide ; branches 1°5 to 2 em. thick, considerably subdivided. Radial corallites usually 
3 to 4mm. long and about 2 mm. diameter; the form is somewhat tubo-labellate, the inner 
part of the wall being thin and short, the outer part of the wall usually bears one or more 
small bud-corallites. In some cases such proliferous corallites may form twigs 6 to 10 mm. 
long and 5 or 6 mm. thick. Immersed or subimmersed corallites are numerous and are 
scattered between the prominent ones quite to the apex of a branch, as in form a. Specimens 
in which the proliferations are well marked bear a general resemblance to M. florida. 
Pacific Ocean: Torres Straits, Great-Barrier Reef, Solomon Islands, ? New Hebrides. 
Form a. 
a-e. Rocky Island Reefs. Saville-Kent Coll. 92. 6.8.81 to 85. (Types.) 
f. Rocky Island Reefs. Saville-Kent Coll. 92.6.8.86. (Var.) 
g. Low Woody Island Reefs. Saville-Kent Coll. 92. 6. 8. 87. 
h-j. Thursday Island. Saville-Kent Coll. 92.6.8.91to 93. (Var.) 
k,l. Green Island. Saville-Kent Coll. 92. 6. 8. 135 & 136. 
m-q. Rocky Island. Sayille-Kent Coll. 92. 6. 8. 139 to 143. 
7. Low Woody Island. Saville-Kent Coll. 92. 6. 8. 308. 
s, ¢. Sta. Anna Is., Solomon Islands. Dr. Guppy [P.]. 84. 12. 11. 26 & 27. 
?u. Mola Is., New Hebrides. W. Wykeham Perry, Esq. [P.]. 75. 10. 27.32. 
Form 0. 
a-c. Capricorn Island. Saville-Kent Coll. 92. 6. 8. 88 to 90. 
32. Madrepora listeri. (Plate XXX. figs. C, D.) 
Corallum subarborescent, oblique, incrusting dead coral, with numerous fusions, Main 
branches 18 cm. long, circular, 1°5 cm. thick, gradually tapering, laxly divided, the subdivisions 
not very spreading, arched upwards a little towards the apex. Axial corallites cylindrical, 
2°5 mm. diameter, 1 to 2 mm. exsert. Radial corallites unequal in size. Near the apex of a 
branch the majority are rather crowded, a little compressed, tubular, with the aperture more 
