NO. 5 CAMBRIAN TRILOBITES RESSER 2'] 



Eldoradia lata, n. sp. 



Ptychoparia ? Vmnarssoni Walcott (part), U. S. Geol. Surv. Monogr. 8, 



p. 47, pi. 9, fig. i8, 1884. 

 Alokistocare Hnnarssoni Walcott (part), Smithsonian Misc. Coll., vol. 64, 



no. 3, p. 185, pi. 25, fig. 7a (heads only), 1916. 



This species differs from E. Hnnarssoni in its wider fixed cheeks. 

 Occurrence same as E. Hnnarssoni (loc. 58a). 

 Cotypcs. — U.S.N.M. no. 90669. 



Eldoradia prospectensis (Walcott) 

 Ptychoparia ? prospectensis Walcott, U. S. Geol. Surv. Monogr. 8, p. 46, pi. 9, 



fig. 20, 1884; U. S. Geol. Surv. Bull. 30, p. 202, pi. 27, fig. 5, 1886. 

 Alokistocare prospectense Walcott, Smithsonian Misc. Coll., vol. 64, no. 3, 



p. 186, pi. 25, fig. 8, 1916. 



Middle Cambrian, Eldorado; (loc. 52a) Prospect Mountain, Eu- 

 reka District, Nevada. 

 Holotype. — U.S.N.M. no. 15441. 



ELRATHIA Walcott, 1924 



Elrafhia Walcott, Smithsonian Misc. Coll., vol. 75, no. 2, p. 56, 1924; idem, 

 no. 3, p. 87, 1925. 



Already species have been referred to Elrathia improperly, as they 

 formerly were to Ptychoparia, consequently great care must be ex- 

 ercised to prevent this name also becoming a " dumping ground." 

 These forms have what might be called the " median " structure of 

 the trilobite, consequently many genera are close to one another. 



Genotype. — Conocorphe (Conocephalites) kingii Meek. 



Range. — Likely confined to the Middle Cambrian. 



ADDITIONAL SPECIES REFERRED TO ELRATHIA 



Elrathia candace (Walcott) 



Ptychoparia candace Walcott, Smithsonian Misc. Coll., vol. 67, no. 2, p. 28, 

 pi. 6, figs. 3, 3a, 1917. 



Middle Cambrian, Gordon ; (loc. 4v) Gordon Creek, Powell County, 

 Montana. 



Cotypes. — U.S.N.M. nos. 63738, 63739, 



Elrathia pylas (Walcott) 



Ptychoparia pylas Walcott (part), Smithsonian Misc. Coll., vol. 67, no. 2, 

 p. 33, pi. 6, figs. 4, 4a, 1917. (Not 4b =^ Alokistocare charax; 4c=zA. 

 gordonensis.) 



Middle Cambrian, Gordon; (loc. 4q) between Gordon and Youngs 

 Creeks, Powell County, Montana. 



Cotypes. — U.S.N.M. nos. 63740, 63741. 



