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 Diplolielia, but include 

 both under Lophohelia. Professor Duncan combines Amphihelia and Diplolielia, and 

 places Lophohelia far away because of its dissepiments. Count Pourtales combines 

 Lophohelia and Amphihelia, and separates with some doubt Diplolielia. 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. (PI. VIII. figs. 9, 10). 



The corallum is small, arborescent in form, formed by alternate gemmation. The 

 surface of the ccenenchym is perfectly smooth, polished, and glistening. There are 

 no costas. 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 Lop>hohelia 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 ccenenchym has a p>ost-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, n. sp. (PI. VIII. 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 costse 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. 



