REPORT ON CORALS — DEEP-SEA MADREPORARIA. 173 



of the species must necessarily be retained instead of Semper's new name, and as they 

 are of the same age I retain the term stohesi as least likely to lead to error. 



We dredged abundant specimens of this coral in the Arafura Sea, very variable in 

 form, and bearing out Professor Semper's conclusions in every way. 



Station 188. Arafura Sea. 28 fathoms. 



Station 190. Arafura Sea. 49 fathoms. 



Flabellum australe, n. sp. (PL VII. figs. 4, a, 5, a, b). 



The adult corallum is very large, dense, and heavy. It is in the form of a com- 

 pressed wedge, triangular in outline. The lateral costse make with one another an 

 angle of from 70 c to 90°. The surfaces of the faces are smooth and glistening, of a 

 brownish colour, marked with evenly curved transverse accretion hues, sometimes with 

 numerous very fine costal markings all over, sometimes with only a few obscure primary 

 and secondary ridges near the base. There is a distinct short cylindrical pedicle. 

 The lateral costae are sharp and rough-edged, somewhat jagged. They usually cease 

 towards the margin of the calicle where the angles of the corallum are evenly rounded 

 off. The form of the mouth of the calicle is extremely elongate and narrow, the ratio of 

 the two axes being about as 100 to 40. The summits of the shorter axis of the calicle 

 are somewhat higher than those of the longer axis, and the upper borders of the faces 

 are evenly curved, with smooth edges. The septa are white, contrasting in colour with 

 the brown wall of the calicle. They are stout, and straight, and covered with fine pointed 

 granules on their faces. All the septa are very low near the margin of the calicle, to 

 which they do not quite extend, a narrow zone of bare calicular margin being present all 

 round the mouth of the calicle. It appears as if then free borders were so to speak cut 

 away close to the calicular margin. The curved free edges of the principal septa bend 

 over and descend nearly vertically to bound the fossa, which is extremely narrow, deep, 

 and long. There are in one adult specimen, that figured, 48 complete septa sensibly equal 

 to one another, and 144 incomplete septa of two different sizes — 192 in all. In one 

 specimen, there are 96 septa on one side, and 92 on the other. In another, 80 on one 

 side, and 85 on the other. Another, 92 on one side, 94 on the other, and 28 of these 

 complete on each side. A young one has 17 complete on each side, and 82 on each side 

 in all. In all the specimens the septa are of three dimensions. The columella lies so 

 deep in the fossa as to be almost invisible. 



This species is well distinguished by its large size, its shape, and the peculiar cutting 

 away, as it were, of the septal borders close to the margin of the calicle. The very 

 young specimens are closely like those of Flabellum patens and Flabellum stohesi, though 

 the adults are extremely different. Flabellum distinctum, Milne-Edwards and Haime, 

 is also in its young stages very like the present species, but differs in having a wider 

 mouth to its calicle. In Flabellum australe this is characteristically narrow. 



