50 NEW YORK STATE MUSEUM 



Urasterella schucherti nov. 

 Plate id, figures 3 and 4; plate 12, figures 4 and 5 



Description. Disk small, formed by the united bases of rays. 

 Rays long, slender, tapering very slowly and very convex on 

 abactinal side. 



Abactinal area of disk shows one larger central plate surrounded 

 by irregularly distributed small, tumid plates. Madreporite, if 

 properly recognized, a small depressed plate with granular surface, 

 situated between the basal supramarginals. Plates on rays distinctly 

 arranged in columns and in quincunx. Three columns of very 

 convex, spinose plates, the radial and supramarginal plates, which 

 are flanked on either side by four columns of smaller plates, the 

 ambital plates, which bear the erect nonarticulate rods characteristic 

 of the genus. Along the edges the spines of the lower ambitals are 

 seen. 



On the actinal side the ray shows wide, shallow, ambulacral 

 grooves, bluntly wedge-shaped ambulacral ossicles which are in one 

 column slightly advanced beyond those of the others and overlap 

 slightly in the medial furrow. The podial openings seem to be 

 narrow and situated between the attenuated ends of the ambulacrals. 

 The adambulacral plates are rather thick disk-shaped, arranged on 

 edge, numbering fifty or more in each column and corresponding in 

 number to the ambulacrals. The adambulacrals continue in some- 

 what diminished size to the oral armature pieces which are blunt, 

 with short, stout, subrectangular ossicles. Outside of the adambula- 

 crals a column of small onion-shaped ambital ossicles is seen, which 

 bear long unarticulated rods, the inframarginal plates being absent 

 in the mature specimen. 



Measurements. The length of a ray from the center (R) is 23 

 mm, the radius of the disk ( r) about 2.5 mm, the basal width of a . 

 ray 3.1 mm. 



Horizon and locality. Chemung beds, Kirkwood, Broome county, 

 N. Y. 



Remarks. We have two specimens of this species from Kirkwood 

 before us, one showing the actinal, the other the abactinal side. This 

 is the only Upper Devonian Urasterella as yet described ; U . 

 a s p e r u 1 a (Roemer) from the Lower Devonian of Germany and 

 U. montana (Stschurowsky) from the Upper Carbonic of 

 Russia are the nearest in age. In aspect and structure it is hardly 

 different from the Ordovician and Silurian forms and is especially 

 similar to the Trenton species U. pulchella. 



