344 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



with fine specimens for comparison I find to exist. The differences 

 between the two species consist principally in the greater expansion 

 of the frontal portion of the glabella of B. howelli. It also has more 

 elongate palpebral lobes, narrower postero-lateral limbs of the crani- 

 dium, one less thoracic segment and a shorter median lobe and a 

 broader border on the pygidium. These differences are shown by 

 the illustrations of the two species on plate 47, figures i and 2. 



The elongate triangular tubercle at the inner end of the thoracic 

 pleural furrows is small in B. howelli as compared with B. ornatus 

 (pi. 46, fig. 4), but it is about as strong as in B. haydeni (pi. 46, fig. 2) 

 and B. {Poliella) powersi (pi. 46, fig. i ) . 



Formation and locality. — Middle Cambrian : (31) Chisholm shale ; 

 Chisholm mine, southwest slope of Ely Mountains, 3 miles (4.8 km.) 

 northwest of Pioche, Lincoln County, Nevada. 



Mr. F. J. Pack records this species from several mine dumps that 

 cut into the Chisholm shale about 2 miles west of Pioche.' 



BATHYURISCUS MANCHURIENSIS Walcott 



Plate 49, figs. 4, 4a-c 



Bathyuriscus manchuriensis Walcott, 191 i, Smithsonian Misc. Coll., Vol. 57, 

 No. 4, pp. 97-99, pl. 16, fig. 4. (Described and discussed as a new species 

 essentially as below.) ■** 



Bathyuriscus manchuriensis Walcott, 1913, Research in China, Vol. 3, p. 219, 

 pi. 23, figs. 2, 2a-/. (Describes and illustrates species.) 



This species is founded on numerous specimens of the cranidium, 

 free cheeks, thoracic segments, and pygidium that are compressed in 

 a fine argillaceous shale. Unfortunately, there are no entire speci- 

 mens of the dorsal shield. 



As restored by combining the free cheeks and cranidium, the 

 cephalon is semicircular in outline and moderately convex. It is 

 bordered by a narrow, slightly rounded margin that is separated by 

 a sharply defined, narrow furrow from the glabella and the slope of 

 the free cheeks. The posterior border is very narrow, elevated, and 

 separated from the fixed cheek by strongly defined furrow ; the pal- 

 pebral lobes are narrow and a little less than one-fourth the length 

 of the cephalon. Genal angles extended into short, sharp, backward- 

 curving spines. The cranidium is broad at the base, narrowing 

 toward the front ; the antero-lateral limbs are very small and dis- 

 appear where the palpebral lobe touches the dorsal furrow : the 



Jour. Geol., Vol. 14, 1906, p. 297. 



