SUBCLASS I 



TRILOBITA 



715 



small free cheeks, and narrovj glabella. Eye-lines present, eyes small. Tliorax of from 

 twelve to twenty-two segments. Cambrian and Ordovician. 



Olenus Da]man (Figs. 1364, I) ; 1371). Glabella only moderately convex, rounded 

 in front. Upjier Cambrian and Ordovician ; Enrojae. 



Eurycare Angelin (Fig. 1372). Ceplialon very sbort and wide, eyes far a^iart. 

 Genal spines long and incurved. Cambrian ; EiU'oi^e. 



Fig. 1374. 



Pi«-1371. Fio.1372. Fio.lSTS. A^dacoplcurakonincU 



Olcnnstruneatus Briinn. Eurycare hrevicmidn Any:. Sao hirsuta (Barr). Barr. Silurian (Etage 

 Cambrian ; Andraruni, Cambrian ; Andrarum, Sweden Cambrian (Etage C) ; D) ; Knclielberg, near 

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



Peltura Milne Edwards. Glabella wide, extending nearly to the front of the 

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

 spines. Upper Cambrian ; Europe and North America. 



Ptychoparia Corda (Figs. 1348, 1364, G). 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 granulose. 

 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 

 of twenty-two segments. Pygidium small. Silurian ; 

 Bohemia. 



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

 137^). Lacks eye-lines. Glabella low and broad. The 

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

 worthy on account of the wealth of information that has 

 been gained concerning the appendages, antennae and 

 other parts in wonderfully preserved remains. Ordovi- 

 cian ; Euroj)e and America,. 



Bathynotus Hall. Eyes long and narrow. Axial 

 lobe wide. Thorax of thirteen segments. Lower Cam- 

 brian ; America. 



Family 5. Solenopleuridae 



Angelin. 



Fig. 1375. 



Triarthr'iis hecki Green. Ordo- 

 vician ; Rome, Xew York. Specimen 

 showing antennae and legs. 8/2 

 (after Beecher). 



Opistlioparia with free cheeks small and widely 

 separated in front, glabella short, convex, tapering toward the front, eyes small. 

 Pygidium short, of few segments. Cambrian and Ordovician. 



