NYMPIIASTER COOMBII. 15 



along the median abactinal lino of the ray throughout, or separated only hy a single 

 series of raedio-radial plates. The marginal plates of both series are granulated, 

 and bear no spines (normally, but occasional incipient spinelets may be present). 

 Abactinal area of the disk covered with large and regularly arranged plates, those 

 in the radial areas well separated, usually hexagonal, more or less tabulate and 

 paxilliform, and frequently bearing an excavate or entrenched pedicellaria. 

 Actinal interradial areas large, confined to the disk. Actinal intermediate plates 

 well defined, covered with uniform granules, and occasionally bearing pedicellariae. 

 Armature of the adambulacral plates arranged in longitudinal series. Madre- 

 poriform body exposed and situated within one third of the distance from the 

 centre to the margin. Large entrenched pedicellarige are freqiiently present on 

 the marginal plates in some species. 



This genus includes a number of recent species brought to light by the deep- 

 sea explorations of late years. It has been found iu the Atlantic, the Pacific, and 

 the Eastern Archipelago. The Atlantic species pass into the abyssal zone, but 

 those inhabiting the Pacific and Eastern Archipelago do not, so far as at present 

 known, extend beyond the continental zone, or in other words they live in depths 

 of less than 500 fathoms. 



The structure and character of the Cretaceous species described in the 

 following pages, so far as they can be made out from the fragmentary condition 

 of the fossils, appear to me to warrant their inclusion iu the genus Nymphaster. 



1. Nymphaster Coombii, Forbes, sp. PI. VII, figs. 1 — 3 ; PL VIII, figs. 1 a, 1 h. 



GoNiASTEK (Asteogonium) Coombii, Forbes, 1848. Memoirs of the Geological 



Survey of Great Britaiu, vol. ii, 

 p. 474. 



— — — — 1850. In Dixou's Geology and 



Fossils of the Tertiar}' and Cre- 

 taceous Formations of Sussei, 

 London, 4to., p. 334, pi. xiiii, 

 fig.G. 



— — — Morris, 185L Catalogue of British Fos- 



sils, 2nd ed., p. 80. 

 Asteogonium Combii, Dujardin and Hupe, 1862. Hist. Nat. 



Zooph. fichin. (Suites aBuffon), 



p. 399, 

 GoMASTEE (Astboooniom) Coombii, Forbes, 1878. In Dixon's Geology of 



Sussex (new edition, Jones), 



p. 367, pi. x.\vi, fig. 6. 



