REPORT ON CORALS — DEEP-SEA MADREPORARIA. 175 



closely-set very fine grooves, which correspond to the septa in position, and appear like 

 fine longitudinal striae. 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 b eight 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. Eight specimens. 



Rhizotrochus, Milne-Edwards and Haime. 



Rhizotrochus fragilis, Pourt. 



Rhizotrochus fragilis, Pourtales, Bull. Mus. Comp. Zool., Harvard, No. 7 ; Deep-Sea Corals, 

 p. 17., pi. 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 Oculinid^e, Verrill. 



Cyathohelia. 



Cyathohelia axillaris, Milne -Edwards and Haime (Hist. Nat. des Cor., vol. ii. 

 p. 110). 



