180 THE VOYAGE OF H.M.S. CHALLENGER. 
better to separate the present form. It differs from both species in the length of its 
calicles in the young condition, and in its very regular distichous gemmation, also in 
the absence of a columella, and in the nature of the striation of the surface. I follow 
Professor Duncan in placing together the genera Amphihelia and Diplohelia, but include 
both under Lophohelia. Professor Duncan combines Amphihelia and Diplohelia, and 
places Lophohelia far away because of its dissepiments. Count Pourtalés combines 
Lophohelia and Amphihelia, and separates with some doubt Diplohelia. Two of the 
specimens are attached to bundles of Hyalonema spicules, which they spread over with 
their bases and cement together. 
Height of the largest branching specimen, 75 mm. Diameter of the mouths of the 
calicles, 2 to 2°5 mm. 
Station 23, off Sombrero Island, Danish West Indies. 450 fathoms. 
Lophohelia arbuscula, n. sp. (Pl. VILL. figs. 9, 10). 
The corallum is small, arborescent in form, formed by alternate gemmation. The 
surface of the ccenenchym is perfectly smooth, polished, and ghstening. There are 
no coste. The septa are very slightly exsert. There are six systems and three 
cycles, the primary and secondary septa being complete. In some calicles there is a 
columella. 
The single fragment only which is figured was obtained. The coral is closely like 
some small specimens of Lophohelia ramea in Professor Duncan’s collection, but differs 
in the complete smoothness and polish of the ccenenchym, The specimen is dead and 
somewhat altered by decomposition ; but, after examining it with the microscope, I do 
not think that the polish of the coenenchym has a post-mortem appearance, or that the 
surface has altered its texture. 
Extreme height of the specimen, 50 mm. Average breadth of the calicles, 2°5 mm. 
Station 194, off Banda Island, East Indies. 200 or 360 fathoms. 
Lophohelia tenuis, nu. sp. (Pl. VII. figs. 11-14). 
The corallum is small and delicate, formed by distichous marginal gemmation. 
There is little or no ccenenchym, the calicles being clearly differentiated, elongate, and 
attenuated at their bases. The surfaces of the calicles are marked with longitudinal very 
fine ridges composed of rows of distinct rounded granules (very badly shown in the 
figure), with which in places ‘the general surface is also covered. The costee are very 
slightly exsert. There are six systems and three cycles ; the free margins of the septa 
are finely serrate, 
Only a fragment of this coral was obtained. It seems to be well distinguished by its 
extremely small size and the peculiar rows of granules upon its surface. It is most 
unfortunate that the figure I have to offer of them is so imperfect. 
