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Show 124 PROF. BELL ON NEW SPECIES OF ASTEROIDEA. [Jan. 17, actinic peculiarity; and the decision can only be given with the aid of evidence which proves or disproves the idea that the species can and does undergo division. Such evidence is here afforded by the specimen in the national collection; for it has the arms of different lengths ; this, of course, points to some of the arms being younger than the others, or, in other words, as having arisen by gemmation after division. The heteractinic, rather than the sexradiate, condition should therefore be regarded as a part of the diagnosis of the species. F R O M I A T U M I D A , n. sp. (Plate VI. figs. 4, 4 a.) Arms and disk more swollen than in most of the species of the genus. R = 45, r = 14 ; R = 35, r = 11*5, o r R = 3*2r (about); breadth of arms at base 14*5, 12*5 millim. All the plates on the actinal surface, with the exception of those of the marginal series, are closely covered with stout spines, from which the spines of the adambulacral series are distinguished by their smaller size. The whole of the abactinal surface is covered by squarish-headed granules, which are all of very much the same size, and are all very regularly distributed ; they are arranged in elliptical aggregations, two or three rows of which extend along the back of the ray, or they are placed between these aggregations ; in the former case they are somewhat more closely packed. The intermediate spaces, in addition to the granules, present a certain number of pores, which, however, are, in comparison with other species of this genus, rare. The madreporic plate is rather nearer the margin than the centre of the disk, and is very similar to the same body in F. milleporella. There are about seventeen marginal plates in both the actinal and abactinal series ; and both sets are covered with granules of a fair size ; and the marginal granules of each set are to be easily distinguished from the more central ones which they surround. For some way along the surface of the arm the dorso-marginal plates are deeper than long; the infero-marginal plates are much more nearly square. There seems to be a large pore at the proximal angle between the two sets of marginal plates ; but as the two specimens on which this description is drawn up have both been dried, it is not possible to speak definitely on the point. The same remark will apply to the pore at the proximal angle of the actinal edge of the infero-marginal plates. The adambulacral spines appear to he arranged in three longitudinal rows. They are subequal in size, and diminish very slightly as they approach the free end of the ray. The space between these spines and the marginal plates is completely occupied with short stout spines, set in tufts on small plates. N o pedicellariae. Ceylon. Presented by M . Kelaart. EXPLANATION OF PLATE VI. Fig. 1. Scales of Calvasterias antipodum, X 4 : 1. 2. Abactinal surface of Cribrella minuta, X 2: 1. 3, 3a. Actinal and abactinal surfaces of Mithrodia victoria, X 2:1. 4, 4a. Actinal and abactinal surfaces of Fromia tumida, showing the arrangement of the plates and spines, X 3 : 2. 4b. Portion of actinal surface, more highly magnified, |