ORDER III 
eleven segments, not distinctly marked off from the thorax. 
Europe and North 
America; also De- 
vonian of North 
America. 
Homalonotus, 
Koenig (Fig. 1321). 
Body usually large, 
elongate, narrowing 
8 
behind, indistinctly 
trilobed ; — glabella 
smooth, flattened and 
almost quadrate ; 
pygidium — elongate 
triangular, posterior 
margin rounded or 
PROPARIA 
635 
Ordovician and Silurian ; 

small, sometimes much 
Sutures 
reduced. 

Fic. 1324. 
Sphaerexochus mirus, 
Beyvr. Silurian; 
Listice, Bohemia. 1/; 
(after Barrande). 
Sphaerexochus, 

pointed, axis with 
ten to fourteen annu- 
lations, sometimes 
smooth and without Fic. 1322. 
apparent segments. Cheirurus insignis, Beyr. Silurian 
Ordovician to De- (Et. E); Kozolup, Bohemia. 1/, 
g (after Barrande). 
vonian; Europe, 
America, and South 
Africa. 
Family 3. Cheiru- 
ridae. Salter. 
Glabella well de- Fic. 1321. Fic. 1323. 
Jined. Free cheeks Homalonotus (Trimerus) delphino- Cephalon of <Amphion Fischeri, 
Eichw. 
Russia. 
cephalus, Green. Silurian ; Ordovician; Pulkowa, 
New York. 
Lockport, 
extending from in front of the genal angles inward to the eyes, and then 
obliquely forward, cutting the anterior margin in front and on each 
side of the glabella. Eyes usually small. Thorax of from nine to 
eighteen segments, generally eleven ; pleura often extended into hollow 
spines. Pygidium small, with from three to five segments ; pleural 
elements commonly produced into spines. Principally Ordovician 
and Silurian, but extending into the Devonian. 
Cheirurus, Beyr. (Figs. 1317, E, 1322). Glabella strongly convex 
and deeply grooved by three pairs of lateral furrows; thoracic 
segments eleven, more rarely nine to thirteen ; pygidium with well- 
marked axis of four annulations, the pleura prolonged into points 
or spines. Species grouped into a number of sub-genera. Ordo- 
vician and Silurian ; Europe and North America. 
Amphion, Pander (Fig. 1328). Cephalon broad and_ short, 
with a distinct rim around the margin; glabella not strongly 
elevated, marked by two pairs of side furrows and short frontal 
furrows. Thoracie segments fifteen to eighteen with inflated 
pleura; pygidium smaller than cephalon, pleural ribs extended 
into spines. Commonly found in the enrolled condition, Ordo- 
vician ; Europe and North America. 
Beyr. (Fig. 1324). Glabella ovoid or globular, with three pairs of 
