52 



four rays bears upon oue upper sloping side four secondary 

 radials and upon the other one secondary radial, which is 

 axillary and bears upon each upper sloping side three tertiary 

 radials, which arrangement gives to each of these rays three 

 arras. In the other ray the third primary radial supports up- 

 on each upper sloping side four secondary radials which gives 

 to it two arms. There are therefore, fourteen ambulacral 

 openings to the vault and fourteen arms in this species. 



The first regular interradials are nine -sided plates followed 

 in the second range by a smaller plate which in turn is fol- 

 lowed by two small plates that unite with the plates of the 

 vault. The azygous area is not materially different from the 

 other areas. 



The vault is convex, most tumid on the azygous side, and 

 bears a subcentral proboscis which is longer on one of the 

 specimens than it is on the specimen illustrated. The plates 

 are large and those about the base of the proboscis bear a 

 central tubercle. There are four elongated ovarian apertures 

 between each radial series and between each single ray and 

 the double ray in each series and two between the other rays 

 which gives to the species forty- eight of these apertures. 



The surface ornamentation and general form of this species 

 resembles D. hammelli, but that species has sixteen arm open- 

 ings to the vault while this one has only fourteen, which will 

 readily distinguish the species. 



Found by J. F. Hammell in the Hamilton Group near 

 Charlestown, Indiana, and now in the collection of Wm. F. E. 

 Gurley. 



DOLATOCKINUS ARROSUS, 11. Sp. 



Plate II T, Fig. 22, bated view; Fig 23, azygous side; Fig. 24, 



summit view. 



Species medium size and elegantly sculptured. Calyx sub 

 cylindrical, not constricted below the arms, broadly truncated 

 at the base. Radial ridges rather large and bearing promi- 

 nent nodes in the middle part of each plate. The surface is 

 further ornamented by long sharp nodes at the center of the 

 interradials and by numerous radiating lines from the central 

 nodes of all the plates. Column large and having a large 

 cinquefoil canal. 



