<>KIU:K 



OPISTHOPARIA 



.1. Nat. M/-. /;, f , K 



//,//<//'// ntire or 



cheeks Mippressed : ,.\vs very large, occupying n.-aily tin- whole an-a ..f ti 



cheeks; thoracic segments five 



grooved; pygidium IIILT, with >lmrt a\i-. 



Ordovician ; Europe. 



Family 4. Proetidae. Harrande. 



CepJidlon ,'li,, lit on, -tin, ;l of fh, irJiol, ,niiii,,il : 

 it mil,. < i/, a, rullii jirtln,;il into gp 



fn in i<l, n- it It tn-o In 1 1 ml li(i.(l loin* 

 In/ obliqn, fnrron:< in front of ///, ,/,,/ 



Free elm!.-* /"///-, separate, >'"////..- 

 extending from il i>o.<t,ri,,r uinniin /'//(//// to 

 the eyes, and then forward, cutting tl,, anterioi 

 Eyes wualiy proinini nt, oft, ,, 

 Thorax of from cii/ltt to twenty-two free (after 'BE 

 segment*, with grooved pleura. Pygidium n*nnllii 

 of munij segments; pleural and axial portions stron'ilij 

 dentate. Ordovician to Permian. 



Proetus, Steininger (Figs. 1275, 1307). Head-shield semicircular, with thickened 

 marginal rim ; glabella well denned, extending nearly to the anterior margin, lateral 

 furrows obsolescent, basal lobes often present. Eyes large, 

 crescentic, near the glabella ; thoracic segments usually ten, 

 pleura grooved; pygidium semicircular, margin entire; axis 

 elevated, segmented ; limb ribbed. Ordovician to Carbon- 

 iferous ; common in the Devonian. 



Phillipsia, Portlock (Fig. 1308). Like Proetua, but with 

 more prominent glabella, strong basal lol.e-, and larger, more 

 segmented pygidium; thoracic segments nine. Thi- --nus 

 replaces Proetus in the 

 later Palaeozoic hori- 

 zona Tlie last surviv- 

 ing species occurs in 

 the Permian of North 

 America. Maximum 

 Fl - 13o: - development in Lower 



Bohf.micus, Corda. ( 1 . ir hn-iiifpTiui< 



,imian(Et.E);Ko, 1 iepm S> l ,, 



Bohemia (after Barrande). ArethUfWa, Hal r. 



(Fig. 1309). (llaLella ^ 



about half the total length of head->liield, jji!;:;^," 1 "' : Kil(lale - 

 contracted towai-d the front, with oblique 

 latei-al t'uri'ows and ba.-al lol.es; fixed '-heeks large; eyefl >mall, situated at the ends of 

 distinct eye-lines from the glabella ; ihorax with twenty-two -hort -c---ineiit- : 'pygidium 

 small. This is the most primitive gemu ..f the family, and the only -ne' 

 archaic eye-lines. The eyes, too, are more distant and f.rwanl than in other 

 and the number of thoracic Moment- i- larger. Ordovician : 



Fi... 



Han. Ordnviciau 

 (Kt. l): 



Family 5. Bronteidae. IJarrande. 



Dorsal Meld broad I ;i '/tijifi,;,/. i ',!,,, I, , less tl,,i,i one-third '/ 

 ylabella raffily*vxpandin<i in front, n-!t J, joint indications "f lol !* 



than the fixed. Faswl sutitrea extending from the posterior margin ./'">' o,],,,,,i *!< "/'.- 

 abruptly inward around the palpebral lobes, and then <///.//''/./ ""' / cutting '// 



