SUBCLASR I 



TRILOBITA 



71i 



small free cheeks, and narrovj glahella. Eye-lines present, eyes small. Thorax of from 

 twelve to twentij-two segments. Cambrian and Ordovician, 



Olenus Dalman (Figs. 1364, 1) ; 1371). Glabclla only inoderately convex, roimded 

 in front. Upper Cambrian and Ordovician ; Europe. 



Eurycare Angelin (Fig. 1372). Cephalon very sbort and wide, eyes far apart. 

 Genal spines long and incurved. Cambrian ; Europe, 



Fig. 1374. 



F^«- 13'1. Fig. 1372. Fio. 1373. AulacopUuraTc<»vincU 



Olennstruncatus Brunn. Eurycare brevicatida Ang. Sao hirsuta (Barr). Barr. Silurian (Etage 

 Cambrian ; Andrarum, Cambrian ; Andrarum, Sweden Cambrian (Etage C) ; D) ; Kuchelberg, near 

 Sweden (after Angelin). (after Angelin). Skrey, Bohemia. Prague. Bohemia. 



Peltura Milne Edwards. Glabella wide, extending neaiiy to tlie 'front of the 

 cephalon. Eyes small, close to tbe front of tbe glabella. Pygidium small, witb short 

 spines. Upper Cambrian ; Europe and North America. 



Ptychoparia Corda (Figs. 1348, 1364, C). Glabella convex and narrow, short, 

 furrowed. Pygidium large. Cambrian ; Europe, Asia and North America. 



Sao Barrande (Figs. 1349, 1354, 1355, 1373). 

 Glabella strongly convex. Thorax of seventeen Seg- 

 ments. Pygidium very small. Surface granulöse. 

 Cambrian ; Bohemia. 



Euloma Angelin. Glabella convex, short, with 

 prominent side lobes, similar to those of Calymene. 

 Pygidium short and wide. Ordovician ; Europe. 



Aulacopleura Corda {Arethusina Barrande) (Fig. 

 1374). Glabella short, small, with basal lobes. Thorax 

 öf twenty-two segments. Pygidium small. Silurian ; 

 Bohemia. 



Triarthrus Green (Figs. 1342, 1344-1345, 1350, 

 1375). Lacks eye-lines. Glabella low and broad. The 

 facial sutures cut the genal angles. This genus is note- 

 wortliy on account of the wealth of Information that has 

 been gained concerning the appendages, antennae and 

 other parts in wonderfully preserved remains. Ordovi- 

 cian ; Europe and America. 



Bathynotus Hall. Eyes long and narrow. Axial 

 lobe wide. Thorax of thirteen segments. Lower Cam- 

 brian ; America. 



Family 5. 



Fig. 1375. 



Triarthrus becki Green. Ordo- 

 vician ; Rome, New York. Specimen 

 showing antennae and ]>'<'<. -''^ 

 (after Beecher). 



Solenopleuridae Angelin. 



Opisthoparia with free cheeks small and widely 

 separated in front, glahella short, convex, tapering toivard the front, eyes small. 

 Pygidium short, offeiv segments. Cambrian and Ordovician. 



