208 ~N. Y. State Museum of Natural History. 



GlYPTOCRINUS ? SUBNODOSUS, 7b, Sp. 



Plate 17, fig. 3. 



Calyx of medium size, obconical, interradial areas slightly depressed. 

 Basal plates hexagonal, height and width subequal, the first in- 

 terradial plate resting on the upper margins. First radial plate hep- 

 tagonal, alternating with the basals. Second radials quadrangular 

 and supporting above the third radials which are heptagonal and form 

 the first bifurcating plate. A second bifurcation has not been observed, 

 although thirty-two plates are shown above. Each alternate plate 

 above the second bears a strong jointed pinnule. 



Above the first interradial plate, which rests on the basal and be- 

 tween the two first radials there is a series of two, three and four, 

 above which there are traces of two more rows. Two series of inter- 

 axillary plates, of one and two plates, respectively, occur above the 

 third radial plate. 



The surface of each radial plate is marked by a small node on the 

 center of a narrow rounded ridge ; the latter bifurcates on the third 

 radial series, and also on the first, sending a branch to the center of the 

 basals. The interradial plates have each a small node at the center, 

 from which a low ridge radiates to each margin to meet those of the 

 adjoining plates. The secondary radials have a light longitudinal 

 ridge, when well preserved. 



Column unusually large for a species of this character. 



When the arms and pinnuise are well preserved they give a pecu- 

 liar bushy appearance when matted down over the calyx. In the 

 position of the first interradial plate and the character of the arms 

 this species departs from the typical form of Glyptocrinus and some 

 other generic reference may ultimately be made of it. 



Formation and locality. Upper portion of the Trenton lime- 

 stone, Trenton Falls, New York. 



MEKOCKFNUS, n. g. 



General appearance of the body not unlike that of some species of 

 Heterocrinus and Dendrocrinus. 



Underbasals pentangular, low and broad in the typical species. 

 Basals hexagonal ; radials pentagonal. Brachials six to seven in each 

 ray, the upper plate pentagonal and supporting the free divisions of 

 the arms above. In the right posterior ray there is a bifurcating 

 plate resting on the radial below, and supporting above on its right 

 sloping side the true brachial series of the arm, and on the left a row 

 of quadrangular plates, vertically arranged. This series of plates 

 resemble the brachial plates, except that they are more elongate. 

 They undoubtedly formed the posterian side of an anal tube, corre 

 sponding in this respect to the same series of plates in the genus 

 locrinus. ' Arms bifurcating frequently, gradually tapering. Piri- 

 nulae unknown. 



