OHPKK I 



HYPOPARLA 





and rjij.i-i- Canil.i-ian and <>rdovi'-Jan rn-k> !' I'.'.ln-ini.i. S 

 Spain, ;nnl America. 



MicriHlfxnix, Kinnions (Fig. li'M. /; . < Vphalon ami pygidium .it'ii-n -li.\vin^ thi-ir 

 segmented nature by annulationa "n their axes; thorax \\ith tin.-.- r i-.ur -<-_'iiient-. 



( 'amlirian. 



Family -2. Harpedidae. Jiarrande. 



Cephalon /"/*/<, m'fli // l>rn,l ni,n;/iini/ taepanrion / ////(/<; <il.ii<ll<i >/-.// </,/ /,/-,,- 

 /'/vr r/cr/.-x ventral, continuoui ; x//////-/ ////////'/'/, /<//<, (////</ ///. outer "/./ "/ 

 Paired simple i>i/r-*j>i,t* ,,r ,,c,-lli\ sin, it,- or <////</., .// /// <//x/,// ,,/.< ,,;" //<//-/////.// 

 eye-lines on tin ji<-l c/ii'/.-x. .< /, ,/r////i/ ,,ntim r<l frin tin- iilnl,,-Uit. 



jive to twenty-nine se<j i a i /if*, /////; /!//(/ ,/,,>,, n<l j,l>m;i. /'//</////'/// 

 (m Harpes) wry small, composed of Imf iln;- < /--/// >-.,//, ,,/x. 

 Oixlovician to Devonian. 



Harpes, in many respect.-, is one ..f the mo.-t inter.-iin- 

 genera of Trilobites, being very unlike other forms. The l.mad 

 hippocrepian pitted limb of the cephalon has its counterpart in 

 Trinucleus and Dionide, although less well developed in these 

 genera. The head is also relatively longer and larger, both 

 features being decidedly larval. It is the only family known in 

 which functional visual spots or ocelli are situated on the fixed 

 cheeks. The young Trinucleus has similar ocelli. The great 

 number of free segments in Haiyes is another primitive 

 character, and the cephalon still remains larger than the thorax 

 and pygidium. 



Harpes, Goldfuss (Figs. 1281, C, 1284). Principally Ordovician and Silurian, 

 although a few Devonian forms are known. 



Harpes unrjula, Stern- 

 b cr}; sp. Ordovician ; 

 Bohemia (after Barrande). 



Family 3. Trinucleidae. Barrande. 



Cephalon larger than the thorax or pygidium ; genal angles produced into .-; 

 Free cheeks continuous, almost wholly ventral, carrying the genal spines ; .<//////. ///<>/<///// 

 or submaryinal. Paired simple eyes or ocelli generally l>. nt In mfulf /.<////> : <-i>miin<1 

 eyes wanting. Thoracic segments five or six, with <in/r,<l j,l, ,i,-<i. 

 Pygidium tr/>iinjnl<u- ; margin entire; axis with a number of 



annufationt : 



grooved, Ordo- 



\ ician and Silurian. 



Trinucleus, 



I, h \\ yd 

 1281,* /', 

 Cephalon with a 

 broad, regularly 

 l>itted liorder, pro- 



dllce<l hehiinl into 



Tri nucleus 



Barr. Ordovician (Et. D) ; 

 Wesela, Boliemia. 1/1- 



i >.\ 



( )rdovirjan ; Kurope and 



ments; axis narrow; pygidium triangular, wide, .-hurt. 

 North America. 



Dionide, Barr. Like Trimn'l'-ti*, l>ut with irregularly punctate 1 .order, and larger 

 pygidium. Ordovician; Europe. 



Ampyx, Dalman (Figs. 1286, 1287). Thorax ami pygidium resemMing / 

 VOL. I L' B 



