720 



ARTHROPODA 



PHYLUM VII 



aboiit one-tliird tlie total widtli. Ordovician and Silurian ; Europe, Asia and North 

 America. 



A n r 



Fk;. 13.S(i. 



A, lJ!'"'ny'< 'Iii'itiifniYolh. Ordovician; Pull<:owa, near 

 St. PctiTsbur-, liussiu. B, C, I. crassicauda Dalman. 

 Ordovician ; J)alck;uiieii, Sweden (after Holm). 



Bumastus Murcliison. Axial lobe very wide ; ceplialon 



and j^ygidiiim smooth. 

 and North America. 

 Thaleofs Conrad, 

 small and elevated. 

 America. 



Ordovician and Silurian ; Europe 



Glabella rather well defined 



Fig. 13b7. 



•j Dikelocephalus minnesotensis 



Ordovician and Silurian ; North Owen. Upper Cambrian ; Wiscon- 

 sin. A, Cranidiuni, B, Pygidiuni 

 (after Hall). 



Family 13. Dikelocephalidae Miller. 



Opisthoparia with large cephalon and pygidium, glahella marked by faint furrows 

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

 pair offlat spines. Upper Cambrian and Lower Ordovician. 



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

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

 Upper Öambrian ; North America. 



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

 Lower Ordovician ; Europe. 



Family 14. Goldiidae Raymond {Bronteidae Angelini). 



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

 cephalon. Glahella much expanded toward the front. Thorax with ten segments 

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

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



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 posterior margin 

 of the pygidium. Devonian; Europe and 

 North America. 



Bronteopsis Nicholson and Etheridge. 

 Cephalon like Goldius; pygidium with 



tudinal ridge. The ribs on the r^uJTfl ^""f ^ ^''^'' ^^^'""^ "^^'^'^ ^' ^ ^^^^S^" 

 li".li..s tl.at tl,o latter appellatto'n wasprroccupreS =*'"*"*"ä '" ^••~'« "' t^e Same author „„ 



Fig. 1388. 



'/" (13eyr). Cephalon. Devonian 



U't. i-,, Konieprus, Bohemia (after Banande). 



