720 



ARTHROPODA 



PHYLUM VII 



about one-tliird the total width. Ordovician and Silurian ; Europe, Asia and North 

 America. 



A B "" ^ 



1380. 



A, lllacnus dalmani Volb. Ordovician ; Pulkowa, near 

 St. Petersburg, Russia. B, C, I. crassicauda Dalman. 

 Ordovician ; Dalekarlien, Sweden (after Holm). 



Bumastus Murchison. Axial lobe very wide ; cephalon 

 and pygidium smooth. Ordovician and Silurian ; Europe 

 and Nortli America. 



Thaleops Conrad. Glaljella rather well defined ;^eyes nikeioccphaius winvesotenns 

 small and elevated. Ordovician and Silurian; North Owen. Upper Cambrian ;^Wiscon- 

 America. 



Fig. 13S7. 



sin. A, Cranidiuui. 

 (after Hall). 



B, Pygidium 



Family 13. Dikelocephalidae Miller. 



Opisthoparia loith large cephalon and pygidium, glabella marked by faint furroivs 

 which extend across it. Eyes large. Pygidium with short axial lobe, and usually a 

 pair of flat spines. Upj)er Cambrian and Lower Ordovician. 



Dikelocephalus Owen (Fig. 1387). Spines on pygidium far apart, short and 

 broad. Complete specimens are known of D. lodensis and D. crassimarginatus. 

 Upper Cambrian ; North America. 



Dikelocephalina Brogger. Spines close together at the posterior end of pygidium. 

 Lower Ordovician ; Europe. 



Family 14. Goldildae Raymond (Bronteidae Angelin^). 



Opisthoparia with eyes close to the glabella and to the posterior margin of the 

 cephalon. Glabella muck expanded toward the front. Thorax with ten segments. 

 Pygidium larger than the cephalon, with short axial lobe. Ordovician to Devonian. 



Goldius de Koninck {Brontes Goldfuss) (Figs. 1340, 1364, H; 1388). Pygidium 



with radiating ribs extending from the end 

 of the axial lobe to the margin. Ordovician 

 to Devonian ; Europe and America. 



Thysanopeltis Corda. Like Goldius, but 

 with small spines along the jiosterior margin 

 of the pygidium. Devonian ; Europe and 

 North America. 



Bronteopsis Nicholson and Etheridge. 

 Cephalon like Goldius ; pygidium with 

 longer axial lobe, behind which is a longi- 

 tudinal ridge. The ribs on the pleural lobes do not radiate from a centre as in 

 Goldius, and they die out before reachiug the margin. Ordovician ; Europe. 



1 The family name " Bronteidae " cannot be retained, as de Kouinck's term Goldius has 

 priority over Bronteus Goldfuss, a term which was substituted for Brontes of the same author on 

 finding that the latter appellation was preoccupied. 



Fiii. 13S8. 



Goldius palifer (Beyr.). Cephalon. Devonian 

 (Et. F) ; Konieprus, Bohemia (after Barrande). ; t 



