OKDKK II 



OPI8THOPABLA 





l'i. LS98) <Vpi,.-,ii,- -hi, -id itenidl 

 smooth, obtusely angular iii fr.nt ; free cheeks short an. I narrow; thora- 



twelve to lom-trrii : pygidium short, nidiinentarv. Cambrian; Kur-.p, 

 America. 



S"o, Barr. (Figs. li'Ts. I :.'!)'.>. <;]al,,.lla .-lightly tap.-ring foril 

 two-thirds tin- I'-n^th of tin- cranidiiun, and having tin. ; di.~tin<t 



I'uiTiiw.- ; thoi 



t t-.-ii ; p ygid i ii in \ .-i v -mal 1. 



( 'anilu-ian : Kino],.-. 



Tri'i rlli i ;/..-. ( ij, ,-n Fi<_'-. 1 i'T 1, 

 i:i>0. (Jlaln-lla larir an- 1 \\.-ll- 



Fio. 1298. 



Schloth. Canihrian ; 

 Ginetz, BohtMnia. 



FIG. 1299. 



So lilt-tutu, Barr. 

 Cambrian; Skrey, 

 Bohemia. 



Fio. 1300. 



Triaftkntt l''-ki, Green. Witli 

 antennae and legs. Ordovician ; 

 Rome, New York. /o (after 

 Beecher). 



fta. i.wi. 



Owen. Cambrian; Wis 



A, Cranidium. B, Pygidium (a(tr 



Hall). 



defined, furrows not continuous; thoracic segments fourteen to >i\t.-u: jih-ura 

 grooved; pygidiiun with six sfgiuents in the axis, margin cntii-c. Onlovii ian ; 

 Ameri<'a and Bcandinavia. 



Owen (Fig. 1301). Cephalou large, crescentic ; glabella nol 

 tending to frontal margin ; eyes well developed ; thoracic st^nu-nts niin-. Pygidium 

 very large, Itroad and t'an-likf, with the sides jn-odiict-d povti-riorly into sjiiii' 

 with four to six riu^s, extending h-. than two-tliirds the length of the pygidium. 

 (Janibrian ; North Anu-rica and Europe. 



Family 3. Asaphidae. Emmrich. 



Gephalon a ml /-//'//W///,,, /i-,7/ //. r,/n r ,>d; ylabeUn fti ./,.<,-i /,/////////'. 

 usually separate. Facial suhin-a extending forward* from ffi> y-x/ -//'.,/ ,-/-/. >,f th- 

 cephalon within tli< ijt'iml mi<ilt .>, mi, I i-nttimj fli, htt<rl or anterior ma -.'/.//// 



uniting in front of the <//"///". /-;/^.>- n*,i,itli/ present) xin<>"i}<, "'// J, r, fulfil, >. 

 of very consi<!<rli/< size, even "mi/,,!,',,,/ ///, ,,iti,-> surfact <>j > ! 

 generally composed of right <>r //// >*//// /^x, ///// rm-iiing frnm ./''' /" '/. /'." 

 large, often with wide ,lnuhlnn: C'amlu'ian to Silurian. 



Asaphus, Brongt. (Cr////"/ ////'".*, Eichw.), (Fi-:.-. 1 - ( ;">, 1288, C, 1302). Cephalic and 

 caudal shields of nearly equal si/c, with 1-i-oad infolded margin ; i^lal'ella expanded, 



