18 



ARTHROPODA 



PHYLUM VII 



Bathyurus Billings (Fig. 1381). 



Fkj. 1381. 



Ikithyunis longispinus Walcott. 

 (Oi(iovician) ; Newport, N.Y. 

 Raymond). 



Black River 

 X Vx (after 



Glabellar fiirrows faint or absent. Pygidium 

 witli four pairs of smootli ribs, and a long^ pro- 

 minent axial lobe. Ordovician ; North America, 

 including Beekmantown beds of Newfoundland. 



Petigurus Raymond. Cephalon like Bath- 

 yurus. Pygidium witli nodose ribs and strongly 

 annulated axial lobe, Ordovician ; Canada and 

 Ireland. 



Bathyuriscus Meek. Glabellar furrows 

 deeper, eyes further forward, and pygidium 

 larger than in Bathyurus. Middle Cambrian ; 

 North America and Asia. 



Bathyurellus Billings. Glabella low, smooth, 

 pointed in front. Cephalon and pygidium 

 witli broad concave borders. Ordovician ; North 

 America. 



Family 11. Asaphidae Burmeister. ■ 



Opisthoparia with large, suh-cqual head and 

 ahdomen shields, prominent eyes, eight segments in 

 the thorax, and with a median vertical suture in 

 the doublure of the cephalon. Middle Cambrian 

 to Ordovician. 



Subfamily A. Ogygiocarinae Raymond. 



Asaphidae with hypostoma rounded or pointed hehind. 



Ogygiocaris Angelin {Ogygia auct. non Brong.) (Fig. 1339). Pygidium with flat, 

 furrowed ribs. Axial lobe very narrow. Facial suture 

 marginal in front of 

 glabella. Ordovician ; 

 Europe, 



Ogygopsis Wal- 

 cott (Fig. 1382). 

 Similar to Ogygio- 

 caris, but with eye- 

 lines, and eyes small 

 and far apart. Middle 

 Cambrian ; British 

 Columbia. 



, Megalaspis Ange- 

 lin (Fig. 1383). 

 Glabella short, 

 cephalon and pygi- 

 dium nearly smooth 

 and sometimes 

 pointed. The facial 

 sutures meet in a 

 point far forward of 

 the glabella. Ordovi- 

 cian ; Europe, Asia, 

 and rarely North 

 America. 



Fig. 1382 





Fig. 1383. 



Megalaspis extenuata Ang. Ordo- 

 vician ; Eäst Gotland, Sweden. 

 Vi (after Angelin). 



