Dr. H. Woodward — M. Cambrian Fossils of the Rockies. 533 



that there are some important differences. The total length of 

 a specimen of B. Howelli is 40 mm. ; the head is 13 mm. in length 

 by 25 mm. in breadth, the thorax 17 mm. in length by 23 mm. in 

 breadth, and the pygidium 10 mm. in length by 20 mm. in breadth. 

 The glabella in B. Eoioelli is broader in front (not straight-sided as 

 in 0. Klotzi), and has four glabellar furrows on each side (not three 

 pairs as in 0. Klotzi). 



Fig. 2. — Bathyuriscus HoiveUi, Walcott, 1886. 

 Middle Cambrian: Mount Stephen, B.C. One-fourth larger than nat. size. 



The head-shield is very short in proportion to its breadth ; the 

 fixed cheeks are narrow, the anterior angle of the eye nearly 

 touching the glabella at its fourth furrow, but expanding again in 

 front, where it surrounds the glabella and forms a rather broad and 

 slightly raised margin to the shield. The ocular border is directed 

 more forward than in 0. Klotzi, and the latero-posterior margin of 

 the fixed cheek, where it unites with the neck-furrow, is rounded, 

 not acute as in 0. Klotzi. The neck-furrow and its pleurae are 

 broad and smooth, and do not carry any tubercles. The free cheeks 

 are rather narrow, and produced backwards into a short and broad 

 spine reaching to the second segment of the thorax. The axis of the 

 body is 8 mm. broad in front and tapers to 5 mm., where the thorax 

 nnites with the pygidium, and is 4 mm. broad at the distal end of 

 the pygidium. 



There are nine ^ thoracic segments in B. Eoioelli and eight in 

 0. Klotzi. There are six coalesced segments in the pygidium of 

 this species and eleven in 0. Klotzi. There are no spines or 

 tubercles on the axis, and the pleuree of the thoracic segments are 

 straight and moderately pointed backward at their extremities. 



Several other species of this genus, which extends from the Middle 

 to the Upper Cambrian (and which was first proposed by Meek in 



1 In Bull. U.S. Geol. Surv., 1886, No. 30, p. 216, Walcott gives the number of 

 thoracic rings as eight ; but in Amer. Jouim. Sci. [3], 1888, vol. xsxvi, p. 165, he 

 correctly gives the number as nine, stating that in the type one segment had been 

 forced beneath the head, a fact that was overlooked "in the original specimen. 

 A comparison of specimens from Mount Stephen with the type from Pioche, Nevada, 

 shows them to be specifically identical. 



