NO. 5 CAMBRIAN TRILOBITES RESSER 25 



furrows usually very faint. Brim variable in width, with a convex pre- 

 glabellar area and a flat, upturned rim. Eyes moderate in size, not 

 much bowed, situated about the middle of the cranidium. Fixed cheeks 

 about half as wide as the glabella. Free cheeks show suture intra- 

 marginal for some distance and have a stout, short genal spine. 



Thorax has 12 to 14 segments in the specimens observed. 



Pygidium wide ; axis well defined except at rear ; up to six or more 

 axial rings are marked out. Pleural lobes very distinctive because 

 both the pleural furrows and grooves are distinctly impressed to the 

 very margin. 



Genotype. — Ehmania weedi, n. sp. 



Range. — Middle Cambrian. 



DESCRIBED SPECIES REFERRED TO EHMANIA 



Ehmania gallatinensis (Meek) 



Conocoryphc (Ptyclwparia) gallatinensis Meek, 6th Ann. Rep. U. S. Geol. 

 Surv. Terr., p. 485, 1873. 



Unfortunately this species is not illustrated, and it is necessary to 

 restrict it to one of the three or more species present in the type lot. 



Middle Cambrian, Meagher ; north of Gallatin River, near Logan, 

 Montana. 



Holotype.— U.S.N. M. no. 7862. 



Ehmania walcotti, n. sp. 



Ptychoparia antiqtiata Walcott (part) (not Salter), U. S. Geol. Surv. Monogr. 

 32, pt. 2, p. 456, pi. 65, fig. ya, 1899. (Not fig. 7 =i E. zveedi.) 



This species was described as a variety. Many fine cranidia and 

 pygidia occur among the specimens not illustrated. 



Middle Cambrian, Meagher; (loc. I5id) south of Gallatin River, 

 Crowfoot Ridge, Yellowstone National Park, Wyoming. 



Cotypes. — U.S.N.M. no. 90667. 



Ehmania weedi, n. sp. Genotype 



Ptychoparia antiquata Walcott (part) (not Salter), U. S. Geol. Surv. Monogr. 

 32, pt. 2, p. 456, pi. 65, fig. 7 (not ya), 1899. 



This species has more strongly developed glabellar furrows than 

 the other described species. 

 Occurrence same as preceding. 

 Holotypc. — U.S.N.M. no. 35234. 



Ehmania oweni (Walcott) 



Ptychoparia oiveni Walcott (not Meek and Hayden), U. S. Geol. Surv. Mongr. 

 8, p. 55, pi. 10, figs. 3, 3a, 1884. (Probably also fig. 18, which is placed 

 with Eteraspis laeviceps; and fig. 22.) 



