62 



ORDER BLASTOIDEA. 

 Family NUCLEOCRINIDiE. 



NUCLEOCRINUS GREENEI, n. sp. 



Plate VI, Fig. 24, side view; Fig. 25, basal view. 



Body elongate, su bo void, depressed in the interradial spaces, 

 so that, viewed from either end, it presents a five-rayed out- 

 line, obtuse at the angles ; most deeply pentalobate at the base, 

 less deeply above; greater width above the middle. 



Base concave; basal plates very small and sunken below the 

 radials. Radial plates very short, embracing the base of the 

 pseudambulacral fields, which consists of a node in the central 

 part of each plate. Pseudambulacral fields very narrow. Inter- 

 radials extend to the summit and are centrally depressed in 

 lanceolate outline, but no suture is discovered, by the side of 

 this lanceolate ornamentation. Azygous interradius wider than 

 the regular areas, most deeply sunken at the base and becom- 

 ing convex or more prominent near the summit of the azygous 

 plate than the pseudambulacra. The azygous plate occupies 

 the entire interradius at the union with the basal plates, it be- 

 comes gently narrower above and abuts upon the outer half of 

 the azygous orifice. The interradial plate is very narrow on 

 each side of the azygous plate, pointed at the lower part, and 

 surrounding the azygous orifice above, it reaches the summit. 



Found by G. K. Greene, in whose honor we have proposed 

 the specific name, in the Upper Helderberg Group, at Louis- 

 ville, Kentucky, and now in the collection of Wm. F. E. Gurley. 



