104 
BULLETIN OF THE LABORATORIES 
hind them, meeting the occipital furrow at a considerable angle, within 
a line directly behind the postero-lateral extremities of the glabella 
proper. Dorsal furrow well defined, running behind the tubercles, 
forward to a point almost even with the anterior margin of the tubercle, 
then back again on the other side. Posterior margin of the regions 
of the glabella an almost straight line running just behind the posterior 
ends of the tubercles. Glabella proper indistinctly marked by 
faint grooves. One of these grooves cuts off from the posterodateral 
extremities of the glabella, parts somewhat larger than the tubercles. 
A second groove (also directed obliquely forward, but at a smaller 
angle) is placed a little anterior to the middle of the glabella, and ex- 
tends about one third of the distance across the glabella. Anterior 
to this are one or two additional grooves, more faint, and also directed 
obliquely forwards, at a slightly greater angle than the last. All of 
these grooves are visible only after careful examination. 
The anterior margin of the head curves quite rapidly downwards, 
so that the general shape of the preserved parts of the head is even 
more convex anteriorly than laterally or posteriorly. Anterior mar- 
gin separated from the rim by a sort of furrow, from which the narrow 
rim rises up at an angle of about 45 degrees. The rim lies in a broad 
curve, passing within a short distance of the groove defining the ante- 
rior portion of the glabella. The facial sutures begin at the rim on a 
line about even with the lateral margins of the tubercles, thence ex- 
tending inwards with a slow curvature, approaching within a very short 
distance of glabella behind its middle, and then apparently extending 
outwards where the outline is lost from want of preservation of the 
fossil. The antero-lateral extremities of the margin are therefore 
almost’rectangularly pointed. 
Length of the glabella to the occipital furrow, 7 mm.; to the pos- 
terior margin, 8.2 mm.; from the posterior margin to the anterior rim, 
10 mm. Breadth of the glabella at its middle, 6.2 mm.; at its poste- 
rior, 6.9 mm.; across the tubercles, 7.4 mm. Distance between the 
tubercles, 4 mm. Length of the anterior rim, about 7.8 mm. 
Locality and position. Soldiers’ Home Quarry, Clinton Group. 
GENUS ILLyLNUS, Dalman. 
III. iLLa^NUS Daytonensis, Hall and Whitfield. 
{Plate XIV, Pigs. 4 a, b; Fig. 6; Figs. 7 a, b, c) 
Species described by Hall and Whitfield in Ohio Pal. Vol. H. 
