I 



I 



NO. 5 UPPER CAMBRIAN TRILOBITES RESSER 57 



BYNUMIELLA, new genus 



It appears that the Byniiuiia stock continued into Franconia time, 

 taking on a somewhat changed form. The alterations in structure 

 may be summed up by stating that they are modifications of Bynniiiia 

 in the direction of average trilobite structure. For instance, the brim 

 structure is retained, but with modification in the direction of reduction 

 to the more normal band form. Likewise the glabella develops con- 

 siderable taper, the dorsal furrow becomes deeper and an occipital 

 furrow separates a neck ring, which is expanded backward in the 

 middle. Only cranidia are known. 



Diagnosis. — Small trilobites with a tapering glabella without fur- 

 rows. Dorsal and occipital furrows are well defined. The simple 

 brim varies in width, but tends to extend forward in the middle, 

 causing the anterior outline of the cranidium to project. 



Genotype. — B. typicalis, new species. 



BYNUMIELLA TYPICALIS, new species 



Plate io, Figures i, 2 



Several small cranidia have been located in the collection, charac- 

 terized by a glabella which tapers to a rounded point, and which is 

 demarcated by the well-defined dorsal furrow. An equally deep occip- 

 ital furrow separates a swollen neck ring. The fixigenes average 

 about the same width as the brim, and the latter has a width equal to 

 one-third the glabellar length. The eyes are small, situated well 

 forward. 



Lyell formation; (loc. 66j) Northeast branch Ranger Brook 

 Canyon, lo miles northwest of Banfif, Sawback Range, Alberta. 



Holotypc. — U.S.N.M. No. 108732a; paratype No. 108732b. 



BYNUMIELLA BRISCOENSIS, new species 



Plate 9, Figure 29 



Several cranidia from the Sabine formation represent Bynumiella. 

 In the holotype cranidium the glabella tapers to a rounded front less 

 sharp than in B. typicalis. The brim width is somewhat less than 

 one-third the glabellar length. Owing to depression of the anterior 

 angles, the brim is convex. The cranidium is moderately arched in 

 both directions. 



Sabine formation ; (loc. i6t) Sinclair Canyon, Brisco Range, British 

 Columbia. 



Holotype. — U.S.N.M. No. 108730. 



