SUBCLASS I 



TRILOBITA 



725 



Grotalocephalns Salter. Similar to Cheirurus but with furrows extending all 

 across the glabella. Silurian and Devonian ; Europe. 



Sphaerexochus Beyrich. (Fig. 1404). Glabella globular, cheeks small. Ordovician 



and Silurian ; Europe and America. 

 Pseudos2)haerexochus Schmidt. 

 Glabella tumid, tapering forward. 

 Pygidium with subequal spines. 

 Ordovician ; Europe and America. 



Nieszkoivskia Schmidt. Glabella 

 tumid or prolonged into a spine 

 behind. Pygidium with two pairs of 

 spines. Ordovician ; Eurojje and 

 America. 



Fifi. 1403. 



Cheirurus insi(jnis Beyr. Sil- 

 urian (Etage E); Kozolup, Bo- 

 hemia. Vl (after Barrande). 



Fio. 1404. 



Sphaerexochus mirus 

 Beyrich. Silurian; 

 Listice, Bolieiiiia. x l/i 

 (after Barrande). 



Fig. 1405. 



Cephalon of Pliomera fischeri 

 (Eichvvald). Ordovician ; Pulkowa, 

 Russia. 



Subfamily B. Pliomerinae Raymond. 



Gheiruridae loith fifteen to nineteen segments in the thorax; jyygidium hemisphericy 

 ivith five flat segments. 



Pliomera Angelin (Amphion Pander) (Fig. 1405). Glabella expanding forward, 

 with two small median lobes on the front. Border of the cephalon denticulate. 

 Ordovician ; Europe. 



Pliomerops Raymond. Similar to Pliomera, but the glabella has parallel sides, 

 and lacks the two small lobes at the front. Ordovician ; Europe and America. 



Placoparia Corda (Fig. 1398, A). Free cheeks are narrow; eyes absent. 

 Ordovician ; Europe. 



Subfamily C. Deiphoninae Raymond. 



Gheiruridae mth a part of the glabella bulbous. 



Beiphon Barrande. (Fig. 1406). Glabella globular, 

 without lateral furrows. Free cheeks minute. Silurian ; 

 Europe and North America. 



Staurocephalus Barrande. Glabella with two pairs 

 of glabellar lobes behind the bulbous portion. Cephalon 

 with a denticulate border, and pygidium similar to that 

 of Pliomera. Silurian ; Europe and North America. 



Sphaerocoryphe Angelin. Glabella with one pair of 

 lobes behind the bulbous portion. Ordovician and 

 Silurian ; Europe and North America. 



Fig. 1406. 



Deiphon forhesi Barr. 

 (Etage E) ; St. Iwan, 

 (after Bariande). 



Silurian 

 Bohemia 



tcith large facets, schizochroal. 



Family 4. Phacopidae Corda. 



Proparia with rather large free checks, eyes large, 

 Thorax with eleven segments. Ordovician to Devonian. 



