lOO 
BULLETIN OF THE LABORATORIES 
tal for the anterior portions of the glabella. The eyes are large. The 
occipital furrow continues as a well defined groove along the pos- 
terior margin of the head. The border anterior to the head is nar- 
row. The character of the postero-lateral corner of the same is un- 
known, but judging from the usual characters of the genus it was 
probably slightly rounded and destitute of -spines. The facial sutures 
follow closely the anterior outline of the glabella to the palpebral lobes, 
from the posterior parts of these they proceed laterally, cutting the 
lateral margins of the head a short distance above, the postero-lateral 
corners. Viewed directly from the front the facial sutures are seen to 
be slightly depressed along the middle of the anterior edge of the gla- 
bella. The same is true of the adjacent rim of the head. 
Length of largest specimen found, 6 mm ; breadth, about 9.6 
mm. Length of glabella to occipital furrow, 5 mm ; greatest width, 
5.7 mm, width just above the third set of furrows, 3.1 mm. Associ- 
ated with these forms is a pigidium which is similar to that of Proetus 
planunarginatus ^ Meek^ of Ohio Devonian strata, but which is placed here 
both on account of its relative frequency at the Soldiers’ Home and 
because other species, undoubtedly of this genus, possess similar 
pygidia. 
These pygidia are broad; the curvature of the anterior edge is 
moderate ; the middle lobe is prominent and very convex, ending ab- 
ruptly posteriorly; segments about nine in a well developed specimen, 
each segment with a tubercle, these forming a median row. Lateral 
lobes moderately convex, with seven or eight segments, becoming in- 
distinct posteriorly. Segments all grooved along the middle, that part 
of the pygidium which lies behind the termination of the middle lobe 
does not show evident segmentation. Posteriorly the margin is thick- 
ened along the edge of the pygidium, so that a groove is formed with- 
in the posterior edge leaving a plane margin which vanishes anteriorly. 
In Proetus planimarginatus the central lobe of the glabella has sim- 
ilar groovings, but the postero-lateral margins are enlarged; there is no 
flat border between its anterior margin and the groove running along 
the edge of the head, the tubercles are also smaller and more nearly 
rounded. The pygidia have the same general form and the same me- 
dian row of tubercles along the middle lobe, but the groove extends 
all around the lateral and posterior margin, and leaves a continuous 
border, from which it derives its name. 
