92 
BULLETIN OF THE LABORATORIES 
bral lobes are rounded, and are situated opposite the anterior half of 
the posterior furrows. The facial sutures anterior to the palpebral 
lobes curve slowly outward toward the anterior edge, then suddenly 
inward again cutting the edge beyond a line passing through the lat- 
eral edge of the tubercles. 
In this genus the facial sutures behind the eyes are parallel for a 
short distance, then curve outward and reach the posterior border of 
the head, usually at a point half way between the glabella and the 
postero-lateral margin of the head. In Cyphaspis the posterior fur- 
rows become deep grooves, dividing the glabella into three distinct 
lobes, of which the central lobe is obovate in form. The middle and 
anterior furrows are usually wanting. The tubercles found in the Ohio 
species have not this signification, but are caused by the bifurcation of 
the occipital furrow. 
Length of smaller specimen, glabella, 3.5 mm; including anterior 
margin, 5 mm. Breadth of glabella, 3. i mm ; including palpebral 
lobes, 4.5 mm ; width measured between the antero-lateral margins of 
the area anterior to the glabella, 4.5 mm. Length of the larger speci- 
men, glabella, 7 mm ; including occipital ring, 8.2 mm; including 
also anterior margin, 10 mm. Width of glabella just above the tuber- 
cles, 7 mm. 
Name signifies bounded, outlined, the limits established, and refers to 
the distinct outline given to the glabella by the surrounding furrow. 
Locality and position. Soldiers Home, near Dayton, Ohio. Clin- 
ton Group. 
III. Proetus . 
(Plate VIII, Fig. 5.) 
Fragments of the glabella of a species are found which are readi- 
ly seen to be distinct from the species just described, but which do not 
admit of a definite determination. There is no distinct, flat border 
anterior to the glabella; instead, the broad groove lies close to the 
glabella anteriorly, separating from the same laterally, and defining 
the raised rim along the anterior edge of the head. This rim makes 
an angle of 45° with the adjacent parts of the head. Only one set of 
grooves is distinctly visible and that is the pair along the postero-lateral 
margins of the glabella. They begin within the anterior portion of 
the palpebral lobes and are directed backwards and inwards at the 
