102 Xortli American 



1'his specimen approaches very closely tlie Griffithides Port- 

 lorkii, Meek and Wortlien, I'roni the Keokuk series of Illinois. . 



BRACHYIHETOPUS McCoy, 1§47. 



Plate II, Fig. 13. 



Generic description. — General form elliptical. Cephalic shields semi, 

 circular, and slightly pointed, about one-third wider than long . Glabella 

 small, somewhat elevated, one-third the width of the entire head, and about 

 one-half the length, having a basal lobe on each side, but no short lateral 

 furrows on the glabella. Neck-furrow distinctly marked, equal in width 

 to the posterior border of the free cheeks. Eyes small, smooth, equal to 

 half the length of the glabella ; no facial suture visible. Free cheeks slight- 

 ly convex, nearly twice as long as they are broad, with no visible suture 

 separating them from one another in front of the glabella. Margin broad 

 and slightly grooved, angles of the cheek produced into spines. Thoracic 

 segments not known. 



Pygidium consisting of a variable number of segments, from 10 to 17, the 

 axis tapering rapidly to a bluntly rounded extremity. Each segment of 

 the axis ornamented with nodes ; ribs with a double furrow extending near- 

 ly to the border, which is smooth and rounded. 



BKACHYMETOPUS LOIilKNSlS, Meek. 



PhilUpsid (Griffithides ^ ) Lodentsis, Meek, 1875, Geol. and Paleonl. Ohio, 

 Vol. 2, part 2. p. 328. pi. 18. tig. 3. 



The original description of this species described a " rather small trilobite, 

 with an elliptic general outline, the length being somewhat less than twice 

 the breadth ; cephalic shield forming rather more than a semicircle, with 

 the posterior lateral angles terminating in acutely pointed spmes that extend 

 back to the third thoracic segment ; anterior and lateral margins rounded in 

 outline, and provided with a more or less tiattened border, ornamented 

 above with a row of small tubercles, that extend back a little upon the pos- 

 terior lateral spines, while it is somewhat thickened and finely striated on 

 the under side ; glabella small, longitudinally ovhI, moderately prominent, 

 sepaiated from the cheeks on each side by a well-defined furrow, but with- 

 out visible lateral furrows of its own (unless there maybe a posterior one on 

 each side separating a little tubercle) ; wiiole surface occupied by about 25 

 distinct tubercles or coarse granules ; eyes small, tubcrculiform, rather pro- 

 minent, and situated near and opposite the posterior third of the glabella, 

 with the visual surface smooth or very minutely reticulated ; cheeks occu- 

 pied by comparatively coarse, proniinent tubercles, like those on the gla- 

 bella ; thorax with middle lobe somewhat wider and higher than the lateral, 

 from which it is separated by well-defined furrows ; segments of mesial 



