MADREPORA. 129 
wall very porous and flattened above. Radial corallites 2 mm. diameter or over, a little 
unequal, with immersed ones scattered between. Aperture large and usually circular. 
Sometimes the radial corallites are not so spreading as in the type form. 
A small subprostrate specimen, from Fiji, agrees with the variety in the form of the 
radial corallites, but the axial corallites are smaller and agree with those of typical 
specimens. 
Pacific Ocean: Fiji, Great-Barrier Reef, Torres Straits, Malacca. 
a. Kandavu, Fiji. H.M.S. ‘Challenger.”? 86. 12. 9. 224. 
b. Fiji Reefs. H.M.S. ‘Challenger’ 86. 12. 9. 225. 
c. ——? ——? 93.4. 7. 161. 
d. Capricorn Islands. J. B. Jukes, Esq. [P.]. 46. 7. 30. 31. 
e-l. Rocky Island. Saville-Kent Coll. 92. 6. 8. 1 to 8. 
m,n. Capricorn Islands. Saville-Kent Coll. 92. 6. 8.17 & 18. 
o. Low Woody Island. Saville-Kent Coll. 92. 6. 8. 19. 
p, q Warrior Island. Saville-Kent Coll. 92. 6. 8. 21 & 22. 
r. Green Island. Saville-Kent Coll. 92. 6. 8. 238. 
Var. labiosa. 
a-g. Rocky Island. Saville-Kent Coll. 92. 6. 8. 9 to11 & 18 to 16, 
h. Green Island. Saville-Kent Coll. 92. 6. 8. 12. 
i. Thursday Island. Saville-Kent Coll. 92. 6. 8. 20. 
j,k. Straits of Malacca, 17 fathoms. Sir E. Belcher [P.]. 42. 12. 2. 86, & 42. 11. 
28. 2. 
129. Madrepora obscura. (Plate XXXII. fig. A.) 
Corallum prostrate, consisting of horizontal main divisions with stout, erect, digitiform 
branchlets on the upper surface, total thickness 9 to 10 em. Main divisions 1°8 cm. 
diameter, more or less confluent. Branchlets on the under surface horizontal, 8 mm. 
diameter and 2 to 4°5 em. long; on these the corallites are subimmersed at the base, but near 
the apex a few stout, spreading, tubular corallites occur, some of which bear buds; others 
between are nariform or appressed tubular. The main divisions give rise on the upper 
surface to arched branches 12 mm. thick, some of which are simple or subsimple, but the 
majority are divided into 3 or 4 digitiform branchlets, with the apices about 2 cm. apart; 
length 3 to 6 cm., diameter over 1 cm., scarcely tapering excepting near the apex, which 
is very blunt. Axial corallites thick, subcylindrical, 3 mm. diameter, not over 1 mm. exsert, 
with slightly rounded margin, surrounded by small bursiform radial corallites as in some speci- 
mens of M. seriata; the star consists of 12 well developed septa. The radial corallites are 
chiefly of two types, nariform and immersed. The prominent ones are nariform, dimidiate, or 
gutter-shaped, with thick wall and rounded margin ; the inner part of the wall is rarely com- 
plete; the immersed corallites extend between the prominent ones to within a short distance 
