INDIANA PALEONTOLOGY. J60. 



The plate sutures are grooved both on the ventral disc and dorsal cup and 

 the ornamentation of the dorsal plates is low, radiating ridges, so crossinig the 

 j)late sutures as to give a pitted appearance between. The deep basal concavity 

 ■extending upward to the level of the q,rm bases is apparently smooth. The or- 

 namentation of the ventral plates is a toothed ridge bordering the suture groove. 



The proboscis is sub central and small 



From the Middle Devonian at the Falls of the Ohio. 



DOLATOCRINU.S VENUSTUS, M. & G., Rowley. 



Plate 47. Figs. 9, 10. 



To this little crinoid at a younger stage an auloporoid coral attached 

 itself and flourished to the inconvenience of its host. Surrounding one arm group 

 it has prevented the development of all but one arm and the crinoid, in its 

 growth, has partially surrounded and imbedded its guest in a calcareous secre- 

 tion. 



The surface about the imbedded tubes, where the secretion thickened, the 

 test is smooth, while the rest of the dorsal surface is highly ornamented with 

 ridges and nodes. 



The specimen has fifteen arm bases, arranged as follows: 3, 3, 4, 4, 1. 



The sub-central proboscis is bent sidewise by the retarded growth of the 

 ^ault near it. Each dorsal plate center is occupied by a strong node and radi- 

 ating lines or ridges traverse the plates from node to node. A low rim sur- 

 rounds the basal concavity. 



The specimen illustrates the fact that arm growth may be retarded or de- 

 stroyed by injury and yet the animal live on ; but this lessening of the normal 

 number of arms does not create a new species. 



Upper Devonian, Speed's Quarry, Clark county, Ind. 



MEGISTOCRINUS EXPANSUS, M. <k G., Rowley. 



Plate 47. Figs. 11, 12, 13. 



Our drawing is of a young specimen but it agrees well with the description 

 of Miller & Gurley's species, even to the number of arms. The anal tube is ex- 

 <}entric and the central dome plate is crowned with a spine. A node is over 

 each arm group. 



The plate ornamentation is indistinct, broken and continuous, radiating or 

 <?oncentric lines. 



Upper Devonian, Clark county, Ind. 



