82 North American 



cone ; on either side an impressed line marking off an accessory portion ; 

 axial segments, 17-19 ; lateral lobes convex ; pi eura3 flattened slightly above, 

 separated by very deep sutures ; margin broad, longitudinally striate, ab- 

 ruptly deflexed ; ribs, 9-12. 



Length of pygidium, 0.35 ; width, 0.45 ; length of axial lobe, 0.27. An- 

 other individual, length, 0.48 ; width, 0.56 ; axial lobe, width, 20 ; length, 

 0.40 inch. The pygidium is generally, if not always, ornamented by minute 

 pustules on the summits of the segments which are borne on the top of a 

 slightly elevated, flattened ridge forming the axis of the annuli " 



Geological position and locality : — VVaverly group, Flint Ridgv, 

 Licking Co., Ohio. 



After a careful study of this species, and the figures of it 

 given by Dr. Herrick, pi. 2, figs. 23 h and 23 c, we are inclined 

 to refer this species to the genus Proetus. 



PKOETUS EI.I.IPTICUS, Meek and Worthen. 



Plate 3, Fig. 3. 

 Proetus elli^iticii 8, Meek and Worthen, 1865, Proc. Acad. Nat. ?ci. Philn., 



p. 267. 

 Proetus ellipticKS, Meek and Worthen, 1868, Palseont. Illinois, Vol. Ill, p. 



460, pi. 14, fig. 8. 



The following is a copy of the description of this species given by the 

 authors : 



"Rather small, entire outline narrow, elliptic ; cephalic shield semi-ellip- 

 tic, about i wider than long, and slightly longer than the thorax — regularly 

 and rather narrowly rounded in front and straight behind, with postero- 

 lateral angles produced into small spines, which extend back to the fourth 

 thoracic segment ; anterior and lateral borders with a narrow marginal rim, 

 strongly deflected upwards, and separated from the cheeks and glabella by 

 a deep furrow. Glabella more prominent than the cheeks, including the 

 neck-segment, a little more twice as long as wide, broader behind than in 

 front, where it is regularly rounded, separated from the cheeks on eacli side 

 by moderately well-defined furrows ; neck-segment more prominent in the 

 middle than any part of the glabella, about twice as wide (antero-posteriorly) 

 as the thoracic segments, and defined by a narrower but distinct neck-fur- 

 row, the continuation of which becomes wider, but rather less sharply im- 

 pressed, as it extends straight across the posterior margin of the cheeks to 

 their lateral marginal furrows ; lateral furrows of the glabella, excepting 

 the posterior ones, nearly obsolete ; posterior lateral lobes small, subovate, 

 and nearly isolated by a rather obscure lateral furrows just in front of each 

 being directed obliquely backwards and inwards, so as to intersect the neck, 

 furrow ; the other two lateral lobes, of which there seem to be indications 



