450 



REMARKS ON NEW SPECIES OF CRINOIDEA, 



Size of Specimen. 



INCHES. 



Diamotor at tho base of free rays, ....... 3.75 



Diameter of pit at summit of first radials, -70 



Depth of basal pit, 20 



Height to free rays, .......... .70 



Locality. — Nueleocrinus bed, Falls of the Ohio, one mile below Jeffersonvillo. 



The arrangement of the arras in groups is somewhat like Dolatocrinus. The size of the 

 species is remarkable. In surface-markings it resembles some of the species of Magesto- 

 crinus, found in the upper crinoidal bed. The plates composing the calyx are very thin, 

 considering the great size of the specimen. It is smaller and less robust than H. plenissi- 

 raus. The many distinct peculiarities of this species will readily serve to distinguish it 

 from all other crinoidcans. 



Hadrocrinus pentagonus, n. a. 

 PI. XXVI, Fig. c. 



Of this species only a single fragment has been obtained. The specimen consists of the 

 basal, and first and second radials of one ray. It most nearly resembles II. discus above. 

 The basalar pit is pentangular; basal pieces quite small; the sides of the first radial pieces 

 diverge slightly, making the sides of the pit very steep ; the exterior surface of the first 

 radials are swollen outward near their junction with the pieces above them; arc subquad- 

 r angular; the truncation of the upper outward corners is very small, producing a very 

 small angular depression between the pieces, at their junction with each other. The upper 

 edges of the first radials arc beveled upward and inward. Upon these beveled edges are 

 placed the second radial, in a line nearly at right angles with the column ; they are pen- 

 tangular (the one seen is of this form), cuneiform, narrow, lateral margins nearly parallel 

 with each other, and by their manner of joining the first radial, the spaces between them 

 are nearly or quite as large as the pieces themselves. All the pieces composing the base 

 are remarkable for their stoutness, and for the singular manner by which the second radial 

 is joined to the first. 



The surface within the pit is well preserved, and shows the markings on the first radials; 

 the surface of the pieces are corrugated by five irregular, rounded ridges, which cross the 

 pieces, and by a multitude of fine lines (furrows), which cross the ridges at right angles 

 with their length ; the furrows between the ridges are smooth. The furrows do not cross 

 them distinctly marked, but gradually fade as they approach them. 



