NO. 22 CAMBRIAN TRILOBITES, 3D CONTRIBUTION RESSER 21 



Lower Cambrian, Mount Whyte; (loc. 35h) Mount Bosworth, and 

 other localities, British Columbia. 

 Holotype.—V.S.ISIM. no. 64388. 



Onchocephalus walcotti, n. sp. 



Crepiccphalus augnsfa Walcott (part), U. S. Geol. Surv. Bull. 30, p. 208, 

 pi. 28, fig. 2b (only), 1886; 10th Ann. Rep. U. S. Geol. Surv., p. 653, pi. 

 96, fig. 9 (only), 1891 ; Smithsonian Alisc. Coll., vol. 64, no. 3, pi. 29, fig. 6 

 (only), 1916 (other figures represent species of Kochaspis). 



This species is much like 0. tJiia, differing in having a wider brim, 

 which makes the whole cranidium relatively longer. 



Lower Cambrian, Pioche ; (loc. 30) 8 miles north of Bennetts 

 Spring, Highland Range, Utah. 



Holotype. — U.S.N.M. no. 61642. 



Onchocephalus parvus (Walcott) 



Anomocare ? parznim Walcott, U. S. Geol. Surv. Mon. 8, p. 59, pi. 9, fig. 17, 

 1884; U. S. Geol. Surv. Bull. 30, p. 209, pi. 25, fig. i, 1886; loth Ann. 

 Rep. U. S. Geol. Surv., p. 653, pi. 96, fig. 2, 1891. 



Lower Cambrian, Pioche; (loc. 51) Prospect Mountain, Eureka 

 District, Nevada. 



Holotype. — U.S.N.M. no. 15426. 



ORYGMASPIS, n. gen. 



Diagnosis. — Cranidium long and narrow, rather fiat in both direc- 

 tions. Glabella over two-thirds the length of the head ; slightly tapered 

 and rounded in front ; dorsal furrow shallow. Three pairs of glabellar 

 furrows, shallow, but clear on exfoliated specimens, scarcely noticeable 

 when the test is preserved. Brim simple, flat, and owing to the slight 

 divergence of the anterior sutures, longer than glabella. In exfoliated 

 specimens a slightly thickened rim is margined in the rear by a row 

 of tubercles. Fixigenes narrow. Eyes situated about the middle oi 

 the head, palpebral lobes not separated by furrow or direction of slope 

 from the fixigene. 



The pygidium is similar to that of Tacuiccphalus Init has a varial)le 

 number of marginal s})ines. 



Outer test evidently smooth except for striations toward the mar- 

 gins. Exfoliated specimens are sparsely granulose, in addition to the 

 mentioned row of tubercles along the anterior furrow. Further, the 

 preglabellar area is vertically lined in such specimens. Libragenes 

 with long spines, striated on their outer surface. 



Genotype. — Ptychoparia llanoensis Walcott. 



Name. — 'o/ovy/x,a = pit ; aCT7ris- = shield. 



