INDIANA PALEONTOLOGY. 89. 



PENT RE MITES PYRIFORMIS, Say, Rowley. 



Plate 29. Figs. 21, 22-23. 



Side and basal views of a malformed specimen. By the introduction of a 

 narrow sixth radial, the slender ambulacrum to the left has quite crowded 

 out the interradial on its right, and more or less deformed the adjoining ambu- 

 lacrum. 



Figure 22 shows this extra radial, which has no groove for the reception 

 of an ambulacrum, but an indistinct longitudinal flattening instead. 



Figure 23 is a basal view of the same specimen showing the hexagonal 

 outline and the broad concave field between the two pairs of crowded ambulacra. 



The summit has the usual four spiracles and the anal opening, but the 

 perforation between the crowded ambulacra is smaller than the rest. 



Figure 12 is a side view of a specimen that has been crushed by a weight 

 on the tip of one ambulacrum, and the injiiry repaired by the secretion of suc- 

 cessive longitudinal bands of stony material, giving the injured radial a pecu- 

 liar linear and banded appearance, much like regular plate sutures. 



All of these specimens of P. pyritormis are from the Kaskaskia limestone 

 near Bowling Green, Ky., and belong to the collection of Mr. G. K. Greene. 



FENTRE MITES GODONI. DeFrance, Rowley. 



Plate 29. Figs. 1, 2, 3, 7, 8. 



Figures 1 and 2 are views of a specimen with six radials, giving to the 

 base the appearance of a six-rayed star. The place in the extra plate that 

 should be the tip of an ambulacrum is slightly grooved. 



Figures 3 and 4 are ventral and side views of a specimen with a pyramid 

 covering the region about the anal opening and the spiracles. It is a five- 

 lobed structure, the lobes being interradial in position. The spiracles and anal 

 opening are not covered over, -however, but appear as small perforations at the 

 top of the pyramid, uncovered, perhaps by the action of water or weather. 

 There passes down the middle of each ambulacrum, for a little distance from 

 the pyramid a low roof-like covering, but the nature of the pyramid and the 

 covering can not be determined on account of the silicified character of the 

 specimen. This strange feature can hardly be due, however, to the overlapping 

 of proximal pinules into a pyramid, as in Etheridge and Carpenter's figure in 

 "The Catalogue of Blastoidea," or similar in construction to the ventral pyra- 

 mid described by Shuman, and afterwards observed by Hambach. It is more 

 probably a structure composed of small plates. 



