OF DENISON UNIVERSITY. 
9 ^ 
groove, the occipital ring seems to extend quite a little distance beyond 
the posterior border. ? - 
A glabella figured by F. B. Meek, in Shumard’s Reports for the 
Geological Survey of Missouri, for 1855, from the Cape Girardeau 
Limestone, Acidaspis HalU, is a similar species, although much smaller. 
Length of glabella in one specimen of moderate size, 8 mm ; in- 
cluding the occipital ring, ii mm; breadth of the mesial lobe, 4.6 
mm ; including the posterior lobes, 1 1 mm, between the inner margin 
of the eyes, 15.3 mm, between the postero-lateral margins, 21 mm; 
convexity of the head, 3 mm. 
Named after Prof. Edward Orton, the distinguished State Geolo- 
gist of Ohio. 
Locality and position. Brown’s Quarry, two miles west of New 
Carlisle, Ohio, Clinton Group. 
Genus PROETUS, Steininger. 
II. Proetus determinatus, sp. 11. 
{Plate VIII, Figs. 2, 3, 3^:.) 
Bathyurus , D. U. Bull., Vol I, p. 103, pi. XIV, fig. 5. 
Glabella conical, convex, sharply defined from the remaining por- 
tions of the head by a distinct furrow ; obscurely marked by three pairs 
of grooves; the posterior pair being inclined at an angle of forty- five 
degrees to the axis of the glabella, cutting off the postero-lateral cor- 
ners; the middle pair, although shorter and less inclined, are still fairly 
distinct; the anterior pair are very indistinct, quite short, and but 
slightly inclined ; in addition three very indistinct pairs of pits may be 
seen, the two anterior pairs are at the ends of the two anterior pairs of 
grooves, the posterior pair are opposite the middle of the posterior 
grooves. In the very distinct occipital furrow beneath the postero- 
lateral corners of the glabella are two almost triangular tubercles 
which add to the conical appearance of the glabella. The occipital 
ring, broad at the middle, narrow at the ends, is supplied with a dis- 
tinct granule near the centre. 
The anterior margin of the head is curved downwards, giving this 
portion of the head a distinctly convex appearance ; the edge is nar- 
row, but plainly elevated at an angle of perhaps forty degrees with 
those parts of the anterior margin immediately adjacent. The palpe- 
