62 THE VOYAGE OF H.M.S. CHALLENGER. 
exactly similar; but its essential structure differs in many particulars which may, 
however, be merely varietal. The calicles are larger and more distinctly circular, some- 
times oval, with the long axis in the line of the branch, but very frequently perpen- 
dicular to it; the septa are less distinct; the proximal and distal lateral pits are 
generally scarcely marked ; and the columella is much wider at its basal part, while its 
free projecting edge is thinner and sharper. For the present I distinguish it as Seriato- 
pora crassa, var. transversa, though it seems almost justifiable to rank it as a distinct 
species, as Servatopora transversa (PI. II. figs. 3¢ and 3d). 
Locality —Mactan Island, Philippines. 
10. Seriatopora hystrix, Dana. 
Seriatopora hystrix, Dana, Zoophytes, p. 521, pl. xlix. fig, 3. 
Two large and very fine specimens of this species were obtained. One possesses 
exactly the characters given by Dana; but the other differs in not having the branchlets 
of the central parts elongate, and subparallel as in Dana’s figure; on the contrary the 
branchlets are divaricately branched throughout and are generally very shortly subulate. 
The two specimens agree so closely, however, in other respects as to be inseparable. 
The latter variety seems to he very close to, if indeed distinct from, the Millepora 
lineata, Linneeus. 
Locality.—Levuka, Fiji. 
11. Seriatopora aculeata, n. sp. (Pl. I. figs. 2-2c). 
Corallum forming a much branched, coalescent, irregularly spreading and subpro- 
strate clump, the branches of which are very short and thick, and are terminated above 
by a very suddenly pointed spine; the branches and branchlets subdivide at very short 
intervals into two, three or more shoots, becoming much swollen at their point of origin, 
so as to resemble rounded knobs, on or about which the new branchlets develop. The 
diameter of the chief branches is about 8 to 10 mm., but often by the coalescence of 
several parts, very thick masses are formed. The swollen terminal knobs of the 
branches are from about 6 to 9 mm. in diameter, and they form the basal part of the 
shoots, which are from 3 to 8 mm. in length, very sharply acuminate, and strong. The 
calicles are rather large, about 0°75 to 1 mm. in diameter, very regularly circular and open, 
often unevenly distant and indistinctly seriate, but very distinctly arranged in six rows 
on the terminal branchlets, rather deep, with two extremely deep lateral pits; the 
upper walls are extremely prominent, evenly rounded, and very strongly and uniformly 
ribbed on the upper surface, the ends projecting at the edge of the wall. The calicles 
thus simulate very closely the reversed short open tubo-nariform calicles of a Madrepora. 
