51 



and, therefore, to have opened externally at the first free arm 

 plates. There are probably twelve of them, but only part can 

 be seen in our specimens. 



There can be very little utility in comparing this species 

 with D. approximatus, the only species heretofore described, 

 having eleven arms, for that species has an elongated calyx, 

 four secondary radials in each series, and four ranges of plates 

 in the interradial areas, with four ovarian pores entering the 

 vault between each of the rays, that are continued in furrow\s 

 across the last interradial plates. It can be of no service to 

 compare it with any species having a different arm formula, 

 for that alone distinguishes it Probably it most resembles D. 

 bulbaceus which has only ten arms. 



Pound by Geo. K. Greene in the Hamilton Group, near 

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

 Gurley. 



DOLATOCR1NUS LAGUNCULA, 11. sp. 



Plate Ilf, Fig. 19, basal view; Fig. 20, side view; Fig. 2l> sum- 

 mit view. 



This species is founded upon five specimens, a medium one 

 being illustrated, -and the largest having a diameter one-fourth 

 greater. Calyx low, expanded at the arms, from three to 

 three and a half times as wide as high and deeply and broadly 

 concave below. Columnar pit funnel-shaped and having with- 

 in it near the top two pentagonal raised ridges running from 

 a tubercle in the middle of each first radial to the next adjoin- 

 ing. Radial ridges merely sharp elevations crossing the plates 

 and interrupted by sharp nodes at the center of each plate. 

 Surface radiately sculptured. Column round, inserted into the 

 cup forme 1 by the basal plates and having a cinquefoil col- 

 umnar canal. 



Basal plates form a round cup so deeply inserted in the 

 calyx that it rises higher than the calyx and ends in the cav 

 ity of the vault. The mouth of the cup is about one- third 

 wider than the diameter of the column. Pirst primary radials 

 about as wide as high, sculptured in the upper part. Second 

 primary radials quadrangular, and about twice as wide as high. 

 Third primary radials expand upw T ard to the lateral angles, 

 longer than the second, pentagonal, axillary and in each of 



