96 North American 



margin, which does nol continue around the front of the glabella ; facial 

 sutures cutting the anterior margin in front of the eyes before, and a little- 

 outside of them behind. Thorax nearly twice as wide as long, distinctly 

 trilobate ; mesial lobe but moderately prominent, nearly twice as wide as 

 either of the lateral lobes, its eight segments merely rounded, and without 

 furrows. Lateral lobes narrow ; pleurae curving moderately downwards at 

 less than half their length out from the axial lobe, but not distinctly genicu- 

 lated, each provided with a furrow extending nearly half way out. 



"Pygidium approaching semi-circular with the anterior lateral angles 

 obliquely truncated ; mesial lobe but slightly wider anteriorly than the late- 

 ral ; segments about eleven ; lateral lobes with eight or nine segments. Sur- 

 face finely granulated, the granules being most distinct on the glabella, and 

 the segments of the mesial lobe of the thorax. 



"This species will be at once distinguished from our P. Purtlockn, from 

 the same horizon, by its much broader and less ventricose glaliella, and the 

 peculiar tuberculiform eyes of that species, as well as by the broader and 

 less prominent mesial lobe of the pygidium, in the form under consideration." 



Locality and pos'tio II. — Crawfordsville, Indiana. Keokuk division of the 

 Lower Carboniferous series.. 



The specimens of this species from Crawfordsville, Indiana, 

 now in the American Museum of Natural History, New York 

 city, Plate III, fi^s. 4, 5, & 10, have a large pyriform glabella, 

 gibbous, overhanging the anterior border. The spines of the 

 free cheeks extend in one specimen to the third segment of 

 the thorax ; PI. Ill, figs. 4 & 5. 



The ribs of the pygidium are double, and die out before reach- 

 ing the edge of the pygidium, leaving a comparatively brond 

 smooth margin. The axis is prominent, about the width of the 

 side lobes anteriorl}', and narrowing posteriorly to about half its 

 anterior width. 



In general this sp.cies jipproaches the Griffilliides globic&ps, 

 Phillips, from the Carboniferous limestone of Yorkshire, Eng- 

 land. 



The glabella of the American species is rather de])ressed con- 

 vex, and slightly overhanging, whereas the English specimen has 

 a very gibbous overhanging glabella. The pygidium of the Eng- 

 lish species has a broad and prominent axis, gradually tai)ering 

 towards the posterior margin, whereas the American species has 

 not the posterior portion of each thoracic segment strongly cor- 

 rugated. 



Specimens of Griffithides hufo have been examined from the 



