NO. 5 CAMBRIAN TRILOBITES 343 



BATHYURISCUS HOWELLI Walcott 



Plate 47, figs, i, la-b 



Bathyuriscus howelli Walcott, i886, Bull. U. S. Geol. Surv., No. 30, p. 216, 



pi. 30, figs. 2, 20. (Describes and illustrates species.) 

 Bathyuriscus hozoelli Walcott, 1888, American Jour. Sci., 3d ser., Vol. 36, 



p. 165. (Considers Embolimus {^ Bathyuriscus'] rotundatus Rominger 



[18S7] identical with this species.) 

 Not Bathyuriscus howelli Matthew, 1899, Trans. Royal Soc. Canada, 2d ser.. 



Vol. 5, Sec. 4, p. 50. (Describes the young of Embolimus [=:: Bathyuris- 

 cus] rotundatus Rominger, following Walcott in identification of the 



latter species as B. howelli.) 

 Bathyuriscus howelli Toll, 1899, Mem. I'Acad. Imp. Sci. St. Petersburg, 



8th ser., Vol. 8, No. 10, p. 30, pl. 2, fig. 11. (Identifies a pygidium from 



the Cambrian of Siberia as B. howelli, and illustrates same.) 

 Not Bathyuriscus howelli Woodward, 1902, Geol. Mag., Dec. 4, Vol. 9, p. 532, 



text fig. 2. (Discusses species when studying specimens of Embolimus 



[=^ Bathyuriscus] rotundata Rominger and illustrates by a diagrammatic 



figure of the latter species.) 

 Bathyuriscus howelli Pack, 1906, Jour. Geol., Vol. 14, p. 296, pl. 2, figs. 2, 2a. 



(Comments on species and illustrates a cranidium and pygidium.) 

 Not Bathyuriscus howelli Walcott, 1908, Smithsonian Misc. Coll., Vol. 53, 



p. 198. (Named as occurring in Spence Shale. The species is now 



referred to Bathyuriscus rotundatus (Rominger).) 

 Bathyuriscus howelli Grabau and Shimer, 1910, North American Index 



Fossils, Vol. 2, p. 287, fig. 1592. (Brief description and reproduces 



Walcott's figure of 1886.) 



This is a rather rare form in the collections I have seen from the 

 vicinity of. Pioche. It occurs in a compact argillaceous shale with a 

 group of species characteristic of the Middle Cambrian fauna. Very 

 little has been added to our knowledge of the species since its first 

 description in 1886. Pack (1906) illustrates a glabella that has a 

 fourth pair of small, short, anterior furrows that with the third pair 

 extend slightly forward from the dorsal furrow. 



In 1881 ^ when reviewing Dr. Rominger's paper on " Primordial 

 Fossils from Mt Stephen " " and some collections from Mt. Stephen 

 I identified Embolimus [^ Bathyuriscus'] rotundatus Rominger as 

 identical with B. howelli. Two errors were made in this paper: I 

 mistook the crushed-down, postero-lateral limb of the cranidium of 

 B. hozuelli for a thoracic segment, thus giving the latter species nine 

 thoracic segments instead of eight, and owing to rather unfavorable 

 specimens of B. rotundatus I did not note other differences which 



* American Jour. Sci., 3d ser., Vol. z^, 1888, p. 165. 



* Proc. Acad. Nat. Sci.. Philadelphia, 1887, pp. 12-19, pl- !• 



