NO. 5 CAMBRIAN TRILOBITES 339 



The fauna associated with this species at the type locahty (4V) as 

 far as identified includes : 



Micromitra (Iphidella) pannula (White) 



Obolus (Westonia) ella (Hall and Whitfield) 



Acrothele colleni Walcott 



Acrothele panderi Walcott 



Winianella simplex Walcott 



Ptychoparia sp. 



Olenopsis americanus Walcott 



Vanuxcmella contracta Walcott 



A single pygidium from locality 4q appears to be identical with the 

 pygidia of this species. It is associated with : 



Micromitra (Iphidella) nyssa Walcott 

 Micromitra (Iphidella) pamiula (White) 

 Wimanella simplex Walcott 

 Acrothele colleni Walcott 

 Ptychoparia 3 spp. 

 Zacanthoides 



Formation and locality. — Lower ? Cambrian : (4V) About 200 feet 

 (61 m.) above the unconformable base of the Cambrian and 75 feet 

 (22.9 m.) above the top of the quartzitic sandstones, in a shale which 

 corresponds in stratigraphic position to shale No. 6 of the Dearborn 

 River section," Gordon Creek, 6 miles from South Fork of Flathead 

 River, Ovando quadrangle (U. S. G. S.), Powell County, Montana. 



Also doubtfully from (locality 4q) about 315 feet (96 m.) above 

 the unconformable base of the Cambrian and 190 feet (57.9 m.) above 

 the top of the quartzitic sandstones in a shale which corresponds in 

 position to the upper part of shale No. 6 of the Dearborn River sec- 

 tion,' on the ridge between Gordon and Youngs Creeks, about halfway 

 between Gordon Mountain and Cardinal Peak, Ovando quadrangle 

 (U. S. G. S.), Powell County, Montana. 



BATHYURISCUS BELUS, new species 



Plate 50, figs. 2, 2a-d 

 This species attains a larger size than either B. anax or B. atossa, 

 and differs from them in minor details of the cranidium and pygidium. 

 There is a faint trace of pleural furrows on the lateral lobes of the 

 pygidium, whereas in B. anax and B. atossa they are strongly defined. 

 The variations from B. belesis are mentioned under that species. 



^ Smithsonian Misc. Coll., Vol. 53, No. 5, 1908, Walcott, Cambrian sections of 

 the Cordilleran area, p. 202. 



