REPORT ON CORALS—DEEP-SEA MADREPORARIA. 175 
closely-set very fine grooves, which correspond to the septa in position, and appear like 
fine longitudinal striz. At the margin of the calicle is an extremely narrow zone of 
glistening white coral substance marking the limit reached by the soft tissues in the 
living coral. The mouth of the calicle is oval in outline, and the summits of the two 
axes are sometimes on the same level, sometimes those of the shorter axis are very 
slightly higher than those of the longer. The axes have to one another a ratio of about 
100 to 150. The margin of the calicle is even, and the septa are not at all exsert. The 
septa are tolerably stout, with their faces covered with pointed granules; they are in 
places bent to accommodate themselves to the curves of the corallum. The full 
number of septa seems to be ninety-six, twenty-four of which are complete ; the 
septa are in the best grown specimens of three different sizes only, but in others four 
different orders in size are distinguishable. There is a tendency to the development of 
more septa, and to the completion of more amongst these, on the side of the calicle 
opposite to the face towards which the corallum is curved. In two smaller specimens, 
ninety-two and eighty-one septa were counted, with twelve septa complete in one, and 
thirteen in the other. The septa sometimes do not quite reach to the margin of the 
calicle, which has its border sometimes very slightly incurved. The fossa is widely open 
with sloping sides, and extends down for nearly half the depth of the calicle. The 
columella is made up of very large tortuous processes not very closely intertwined. 
Extreme height of the largest specimen, 48 mm. Long diameter of the calicle, 40 
mm. Short diameter, 25 mm. 
Station 320, off the mouth of the Rio de la Plata. 600 fathoms. Hight specimens. 
Rhizotrochus, Milne-Edwards and Haime. 
Rhizotrochus fragilis, Pourt. 
Rhizotrochus fragilis, Pourtalés, Bull. Mus. Comp. Zool., Harvard, No. 7; Deep-Sea Corals, 
p. 17., pl. iv. figs. 1-4. 
Station 142, off the Cape of Good Hope. 150 fathoms. One specimen. 
A very broken fragment of the same species (?). Off Api Island, New Hebrides. 50 
to 125 fathoms. 
Family Ocutinip&, Verrill. 
Cyathohelia. 
Cyathohelia amillaris, Milne-Edwards and Haime (Hist. Nat. des Cor., vol. ii. 
p- 110). 
