MELOCRINID^. 295 



Melocrinus nobilissimus (Hall). 

 Plate XXIII. Figs, la, 2, S. 



1859. Mariacrinus nobilissimus — Hall ; Palseont. N- Y., Vol. III., p. 105, Plate 2, Eigs. 1-4, and Plate 



2A, Pig. 1. 

 1881. Melocrinus nobilissimus — ^\ and Sp. ; Revision Palseocr., Part II., p. 122. 



A rather large species. Dorsal cup higher than wide, obconical, obtusely 

 pentangular above the costals owing to a depression in the upper portions 

 of the interradial spaces. The tubular appendages supporting the arms con- 

 sisting of two contiguous trunks, which are composed dorsally of two rows of 

 plates. Plates marked with obscure radiating ridges ; the suture lines well 

 defined, with a shallow pit at each angle. 



Basals wider than long, formed into a small subcyhndrical cup, not pro- 

 jecting beyond the column. Radials larger than the costals, about as wide 

 as long. The second costals with an obtuse angle above. Distichals 3 X 10, 

 about half the size of the costals, the upper ones axillary and supporting 

 upon their outer sloping faces a lateral arm, of which the four or f\YQ proxi- 

 mal plates, which are longer, are incorporated into the calyx ; while the inner 

 sloping faces are followed by a row of from six to seven palmars. The latter 

 form a vertical line with the distichals, and the plates of adjoining divisions 

 are connected laterally, except the two proximal ones of each side, between 

 which are interposed small irregular interdistichals. The fourth and fifth 

 orders of brachials consist of fiYe plates, the sixth and all orders to the ninth 

 of four, the succeeding ones of three, and those near the top of but two 

 pieces. The brachials are arranged longitudinally, and connected suturally 

 with those of the opposite branch, so as to form a compound, free tubular 

 appendage, from which the arms are given off at opposite sides, the axillaries 

 supporting on their longer sides the next order of brachials, and on their 

 shorter ones an arm. There are about thirty arms to each side of the ray, 

 rising to the same general height ; all composed from the second plate up of 

 two series of interlocking pieces, and all pinnule-bearing. Eegular inter- 

 radial spaces narrow but long; the first plate rests within a deep notch 

 between two radials, and is somewhat larger than the others ; the succeeding 

 ones are not arranged in horizontal rows, but alternate with one another; 

 they are hexagonal, and the upper lateral faces of the one plate rest against 

 the lower lateral faces of the other, thus forming two longitudinal rows side 

 by side, each composed of about twelve plates, which decrease in size 



