PAPERS ON GEOLOGY 27% 
Pygidium transversely sub-elliptical in outline, moderately 
convex, length 52 mm, width slightly less than twice the length, 
without apparent concave border, although when only partially 
exfoliated undulating lines sub-parallel with margin are present 
near the border. Axial lobe poorly defined, much the widest 
anteriorly, the posterior end usually more prominent than the 
other portions, without annulations. Fragments of the test 
this species are common in the Orchard Creek shale north of 
Thebes, Illinois. 
Endymionia bellatula n. sp. 
riate 1 big. 3. 
Description: The species here described is so unlike any 
other known trilobite that a comparison with other forms is 
unnecessary. The genus was described by Billings to receive 
the only species previously known in North America (Endy- 
muionia meeki Billings), which was found in rocks of early 
Ordovician (Canadian) age in eastern Quebec. 
In the species here described the entire test is sub-elliptical 
in outline, the ratio of length and width as 7 to 5; lateral mar- 
gins nearly straight, anterior and posterior borders rounded. 
Cranidium transversely semi-elliptical to broadly sub-trian- 
gular in outline, length slightly more than one-third the entire 
length of the test, anterior portion broadly rounded, Glabella 
convex, nearly as wide as long, reaching the anterior margin, 
widest in the anterior portion, bordered laterally by well de- 
fined dorsal furrows, without lateral furrows, occipital furrow 
not prominent. The greatest width of the glabella is equal 
to or slightly greater than one-half the width of the cephalon. 
Outside the dorsal furrows the cheeks are sub-triangular in 
outline, smooth, gently convex, the outer margin gently round- 
ed, and genal angles rounded, without spines. The position 
of the eyes and of the facial suture cannot be distinguished. 
Thorax a little shorter than the cephalon, less than half as 
long as wide, composed of 5 segments; axial lobe defined by 
distinct dorsal furrows, slightly narrower than the pleural 
lobes, the extremities of the segments truncated bluntly, pleural 
portions of the segments marked on the dorsal surface by an 
undulating furrow. 
