392 The Ohio Journal of Science [Vol. XIX, No. 7, 



backward, and appear more or less parallel to the sides of the axial lobe, 

 when viewed from above. In consequence, the posterior ribs have a 

 slightly converging appearance posteriorly, and lie close to the axial 

 lobe. At their distal ends the pleural ribs are lengthened parallel to 

 the margin of the pygidium into a form slightly resembhng the foot of a 

 flattened stocking." In consequence, the margin of the pygidium is 

 marked by 7 crenulations ; the last pair of ribs does not reach the margin 

 but terminates at a nearly obsolete point a little over a millimeter 

 bevond the end of the axial lobe. When viewed from the lower side 

 of the pygidium it is seen that the margin of the pygidium is abruptly 

 infolded for a distance of about a millimeter beyond the margin of the 

 pygidium as viewed from above. This infolded marginal part is smooth, 

 the pleural ribs terminating at the sharp angle of infolding. The 

 infolded part forms an angle of about 170 or 160 degrees with a hori- 

 zontal plane passiiig through this margin. The grooves between the 

 anterior pleural ribs are about half a millimeter in width. At the 

 bottom of each groove there is a slight elevation, extending along its 

 entire length. The tubercles on the pleural ribs are irregularly arranged, 

 the location of the more prominent tubercles apparently being constant. 

 In the accompanying figure, the more prominent tubercles have been 

 accentuated. On the first pleural rib there is a tubercle nearly a third 

 of its length from the axial lobe, the corresponding tubercle on the next 

 rib being situated a little closer. On the third pleural rib the tubercle 

 occurs nearly at mid-length. The tubercles on the fourth and fifth 

 ribs are near the axial lobe, that on the fifth rib being sHghtly more dis- 

 tant. The tubercle on the sixth rib is a little closer than mid-length, 

 that on the seventh rib is much closer to the axial lobe, and that on 

 the eighth rib is only indistinctly defined near its anterior end. 



Locality and Position: In the Holophragma zone, at the 

 top of the upper or Lilley division of the West Union formation, 

 in the Zink or Corporation quarry, within the eastern border 

 of Hillsboro, Ohio. 



Remarks : Pygidia having the same arrangement of tubercles 

 on the pleural ribs occur also in the Waco division of the Crab 

 Orchard formation, at Irvine, Kentucky. The same arrange- 

 ment is seen also in typical Encrinurus ornatus, described by 

 Hall and Whitfield from the Cedarville dolomite at Eaton and 

 Yellow Springs, Ohio; but the latter appears to be a larger 

 species and the glabella is more convex. The exact arrange- 

 ment of the tubercles in Encrinurus reflexus Raymond (Bull. 

 Mus. Comp. Zool. Harvard, 1916, p. 25, pi. 3, figs. 7, 8), from 

 the Niagaran at Wauwatosa, Wisconsin, is unknown, but the 

 figure of the pygidium bears a close resemblance to known 

 specimens of Encrinurus ornatus. 



