NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES '89 



is necessary to make several species from among the numerous 

 specimens from Texas. It will be noted that a different pygidium 

 has here been assigned to this than that given by Shumard. It is 

 true that the pygidium apparently referred to in Shumard's descrip- 

 tion occurs with the heads of Elvinia, but at other localities, some 

 far removed from Texas, only the type of pygidium here illustrated' 

 is associated with these heads wherever they occur. 



Formation and locality. — Upper Cambrian: (68) Cap Mountain 

 formation. Packsaddle Mountain, Llano County. 



(70) Baldy Mountain, Morgans Creek, eight miles (12.9 km.) 

 northwest of Burnet, Burnet County. Texas. 



Genus EUREKIA Walcott 



Eurekia Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, pp. 56, 57. 



Description. — Eurekia is represented by numerous specimens of 

 the cranidium, free cheeks and associated pygidium. The strongly 

 convex glabella with its deep dorsal furrows, the narrow upturned 

 frontal border, narrow fixed cheeks and palpebral lobes, combine to 

 give the cranidium a very distinctive character as does the associated 

 pygidium (pi. iG, fig. 17). As at present constituted the genus 

 includes species both with and without glabellar furrows. It may be 

 that as the study of this group advances beyond its present incom- 

 plete stage, the species without glabellar furrows will adhere to Cor- 

 binia rather than to Eurekia, but the structure of the frontal rim 

 and of the pygidium seems to prevent this. The eyes of Corbinia are 

 also smaller than in Eurekia. 



There are several described species that appear to belong to the 

 genus. 



Dicellocephaliis ? angustifroits Walcott, 1884, Monogr. Geol. Surv., 

 Vol. 8, p. 42, pi. 10, figs. I, la, lb. 



Ptychoparia (Etiloma) dissimilis Walcott, 1884, Monogr. U. S. Geol. 

 Surv., Vol. 8, p. 51, pi. 9, fig. 28. 



Conocephalites cos Hall, 1863, i6th Ann. Rept. State Cabinet Nat. 

 Hist, p. 151, pi. 7, fig. 24, pi. 8, figs. 8, 9. 



Conocephalites binodosus Hall, 1863, i6th Ann. Rept. State Cabinet 

 Nat. Hist, p. 160, pi. 7, fig. 47. Hall did not associate any head with this 

 species but later collections have furnished numerous examples. It has 

 recently been described by Clark * as Bayiieldia Unkelnburgi. 



Genotype. — Eurekia granulosa Walcott. 



Range. — Upper Cambrian : Great Basin, Rocky Mountains and 

 Mississippi Valley (north and south). 



^ Clark, 1924, Bull. American Pal., Vol. 10, No. 41, p. 32, pi. 4, fig. 7. 



