Abstract
Diagnosis. —A Hydreionocrinus with cup depressed and bowl-shaped, flattened on posterior interradius, stem-facet depressed in IBB circlet, having plates equably curved and closely covered with fine pustules. With an interbrachial plate resting in a notch between the radials; in the post. IR. the corresponding notch is between anal x and l. post. R. Horizon. —Middle Carboniferous, Poolvash Limestone (Upper Dibunophyllum zone, fide Wheelton Hind, 1907, p. 148, and 1909, p. 167). Locality. —Poolvash Bay, Isle of Man. Holotype. —A complete cup collected by Mr. James L. Begg, and presented by him to the Geological Department of the British Museum, registered E 21591. Description of the unique Holotype. —Cup depressed and bowl-shaped. IBB not impressed, but slightly excavated for the stem-facet. Cup-plates equable or very faintly tumid; sutures flush or almost imperceptibly depressed; surface with a uniform shagreen-like ornament of pustules, 3.5 or 4 in 1 mm. linear. The sub-pentagonal outline and the regular slope of the sides of the cup are disturbed by the anal area, which is more flattened, i.e., approaches the vertical more rapidly. IBB. form an almost regular pentagon, with sides normally straight. BB. therefore pentagonal, except This 250-word extract was created in the absence of an abstract
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