INDIANA PALAEONTOLOGY. isz 



DOLATOCRINUS PRECIOSUS, M. & G., Rowley. 



Plate 45. Figs. 1, 2, 3. 



Body depressed. Dorsal cup flattened to the middle of the first interradials 

 but with no concavity except about the stem base and that is insignificant. 



A rim surrounds the columnar cicatrix. The columnar canal is medium in 

 size and pentalobate. Column rather large. The first radials are wider than 

 long, with a strong central tubercular node from which radiate out to the plate 

 margins lines of small nodes and short acute ridges, the latter between first ra- 

 dial centers only and three in number. (The drawing shows but two.) 



The second and third radials are wider than long, with central tubercular 

 nodes and radiating linesj of smaller nodes or short ridges. 



Of the two plates resting on the upper edges of the third radial, one is 

 bifurcating and supporting above a series of two or three plates to the arm 

 bases. All of these radial plates have the strong central node and radiating 

 ridges or confluent nodes, the central tubercles of all the radial plates being con- 

 nected by a low sharp ridge. 



The first interradial plates are about as wide as long and eight sided, with 

 a strong central node from which radiate outward to the sutures numerous lines 

 of smaller nodes and ridges. The second interradial is smaller than the first 

 and supports above a still smaller plate, all being ornamented alike, the entire 

 series being 1, 1, 1, except the anal, which is 1, 1, 3. The second plate of the 

 anal interradial is smaller than the same plate in the other interradial areas, 

 while the three plates above are quite small and lie between the arm lobes. 



The ventral disk is but little elevated, the inter-ambulacral spaces de- 

 pressed, making the arm lobes strong and distinct. The anal tube is rather 

 slender and located sub-centrally, its plates being strongly nodose or tuburcu- 

 lar. The central dome plate and the base of the proboscis are surrounded by 

 a ring of seven plates, the anterior four being much the larger. Two of these 

 latter being located ambulacrally and two inter-ambulacrally. Of the three 

 smaller plates of this ring, two are ambulacrally placed and the oiie inter- 

 ambulacrally situated is in the anal depression. 



The next ring of plates is oomposed of paired, elongate, inter-ambulacral 

 pieces, separated by a single ambulacral plate followed below by three other 

 smaller ambulacral pieces. 



The elongate inter-ambulacral pieces, largest and longest in the two anter- 

 ior depressions, fill the valleys below the first ring of plates, except in the anal 

 area where there are three or four small plates. 



