710 



ARTHROPODA 



PHYLUM VTI 



Family 1. Agnostidae M'Coy. 



Hypoparia with head and ahdomen shields similar ; free cheeks not visihle from the 

 dorsal side. Thorax with two segments. Cambrian and Ordovician. 



Subfamily A. Condylopyginae Raymond. 



Agnostidae with many-lohed shields, long glabella which expands toward the front, 

 and long and hroad axial lohe on pygidium. 



Gondylopyge Corda. Anterior lobe of glabella broad. Pygidium 

 with three pairs of middle - lobes, and a broad end-lobe. Middle 

 Cambrian ; Europe and North America. 



Pleurodenium Corda (Fig. 1358). Similar to Gondylopyge, but 

 with anterior lobe of glabella flattened, and crossed by radiating 

 grooves. Cambrian ; Europe. 



Diplagnostus Jaekel. Anterior middle-lobe divided. Axial lobe 

 of pygidium pointed behind. Cambrian ; Europe, 



Peronopsis Corda. Anterior middle lobe of glabella simple, not 

 wider than the part behind. Accessory lobes present at base of 

 granuiatum (Barr.), glabella. Middle Cambrian ; Europe and North America. 



Cambrian ; Skrey, 

 Bohemia. ß/j (after 

 Barrande). 



Subfamily B. Arthrorachinae Raymond. 



Agnostidae with middle lohe of glahella short and simple; small accessory lohes 

 present at läse of glahella. 



Arthrorachis Corda. Ordovician ; Europe and North America. 

 Hypagnostus Jaekel. Axial lobe of pygidium narrow, pointed behind. 



Fig. 1358. 

 Pleurocteniw) 





Subfamily C. Agnostinae Jaekel. 



Agnostidae with hoth shields sculptured. Middle lohe of cephalon long, narroived 

 toward the front. Accessory lohes always present. 



Agnostus Brongniart (Figs. 1357, A ; 1359). Surface 

 smooth ; accessory lobes simple. Cambrian ; Europe and 

 North America. 



Ptychagnostus Jaekel. Surface wrinkled or otherwise 

 ornamented. Accessory lobes double. Cambrian ; Europe 

 and North America. Fig. 1350. 



Agnostus pisiformis (Linn.). 

 Cambrian ; Andrarum, Svveden. 



Sabfamüy D. Phalacrominae Corda. ^S^ofur^'^S^ltZkAZ^i 



A i-j -,7 T . •■ , cephala and pygidia. 



Agnostidae with shields scarcely lohed. 



OrdSan' Eiiro^; ^'^'^^' ^""^^ ""^ ''^^'^^'''' ^''^ pygidium barely indicated- 



Phalacrorm Corda. Cephalon and pygidium without lobes. Cambrian and 

 üi-dovician ; Europe and North America. 



Family 2. Eodiscidae Raymond. 



seameZ^ZllT^^ "T^ ^J'' f.'''^' '''' visihle from the dorsal ^de ; thorax of three 

 Segments , pygidium annulated. Cambrian. 



