102 BULLETIN OF THE 



About two liundred and fifty specimens of the different varieties of this 

 species were obtained, so that from the various expeditions we must have 

 about a thousand specimens. Among that number I have not found a single 

 one attached, or showing marks of adherence. 



There are four well-marked forms, more or less connected by intermediate 

 ones, though, on the whole, specimens showing the passage from one form to 

 another are rare, and one form generally prevails in each particular dredging. 



Variety cf, Agassizii. PI. I. Fig. 2. 



The typical form on which I based my first description, equicostate, with 

 more or less conical base, costae rather prominent, sharp, finely serrate and 

 granulate. (Deep-Sea Corals, PL IL Figs. 1, 2, 3. Lindstrom, Contr, to 

 Actinol. of Atl. Oc, PI. II. Figs. 15, 16, 17. Moseley, Madrep. of the 

 Challenger Exped., PL II. Figs. 2 and 3.) This form approaches nearest 

 D. italicus; there are specimens in which the spines of the costae are large and 

 blunt, and resemble the bead-like grains of the fossil species. (PI. I. Fig. 3.) 

 This was considered by Reuss and by myself as the chief specific difference 

 between the fossil and living forms. The variety australiensis, Duncan, does 

 not differ particularly from this one ; but D. orientalis, Duncan, is different. 

 The corals referred to this genus by Mr. Tenison-Woods do not appear to me 

 to belong here, as far as the very rough figures allow me to judge. 



Variety ^. PL I. Fig. 4. 



Like the preceding in most particulars, but more hemispherical in outline ; 

 the costse are a little more differentiated, and the primaries have sometimes a 

 slight enlargement or blunt knob in the middle of their length, showing a 

 tendency at one period of their growth to form the points characteristic of the 

 next form, or variety calcar. The pali in this form are not very prominent, 

 and the junction of the septa of younger with those of older cycles occurs far 

 down towards the centre of the calicle. Some specimens resemble very much 

 Trochocyathus ohesus, one specimen of which from Tortone, Italy, in the Muse- 

 um collection, has likewise only one knob or blimt spine on the primary costoe. 



Variety y, calcar. PI. I. Fig. 5. 



(Deep- Sea Corals, PL IL Figs. 4 and 5, and PL V. Figs. 9 and 10 ; and 

 Hassler Exp., PL VI. Fig. 11. Lindstrom, L c, PL I. Fig. 13, PI. II. Figs. 14, 

 18, 19.) I give the figure (PL I. Fig. 1) of the specimen, which has induced 

 me to consider this only a variety of the other form. Besides the specimen 

 with double horns figured in Deep-Sea Corals (PL V. Fig. 9), there is another 

 one in the present set with three or four horns on the primary costse, appar- 

 ently the result of an injury. Reuss mentions a specimen of D. italicus with 

 remarkably thickened, and almost lamelliform, primary and secondary septa, 

 60 that it seems that the fossil form had also the tendency to vary in the same 

 manner. 



