NO. 4 CAMBRIAN TRILOBITES, 2D CONTRIBUTION RESSER 25 



In this and related species the glabella is more convex than the 

 remainder of the cranidium and hence appears more distinctly sepa- 

 rated than in the genotype. 



Upper Cambrian, Secret Canyon; (loc. 59) Combs Peak, and 

 (loc. 61) Hamburg Mine, Eureka District, Nevada. 



Holotype. — U.S.N.M. no. 24559. 



LABRADORIA, n. gen. 



A single species among the abundant Lower Cambrian trilobites of 

 the Forteau formation can be referred to no other genus and must, 

 therefore, be given a name. It is likely, however, that additional 

 species will be discovered among the large collections from beds of 

 similar age in the Appalachians. 



Diagnosis. — Cranidium alone known. Glabella large, convex, rising 

 above the fixed cheeks and extending forward to the rim. A strong 

 occipital furrow separates a neck ring which is extended into a stout 

 spine. Three sets of glabellar furrows extend across the glabella, slop- 

 ing backward in the usual manner. Eyes fairly large, situated well 

 back. Eye lines heavy. Brim consists of a thickened rim only. Facial 

 sutures diverge slightly anterior to the eyes. 



Genotype. — Conocephalites miser Billings. 



Range. — Lower Cambrian of the Appalachians. 



Labradoria miser (Billings) 



Conocephalites miser Billings, Geol. Vermont, vol. 2, p. 950, fig. 354, 1861 ; 



Pal. Foss., Geol. Surv. Canada, pt. i, p. 11, fig. 14, 1861. 

 Ptychoparia miser Walcott, U. S. GeoL Surv. Bull. 30, p. 199, pi. 27, fig. 2, 



1886; loth Ann. Rep. U. S. Geol. Surv., p. 651, pi. 96, fig. 8, 1891. 



Billings described the species, illustrating only the glabella. Sub- 

 sequently, Whiteaves and Walcott restudied Billings' material, and 

 Walcott published a figure of a more complete specimen, which thus 

 became the neoholotype and on which the species must rest. 



Lower Cambrian, Forteau ; L'Anse au Loup, Straits of Belle Isle, 

 Labrador. 



Neoholotype. — Nat. Mus. Canada; cast. U.S.N.M. no. 15444. 



MODOCIA Walcott, 1924 



Modocia penfieldi (Walcott) 



Ptychoparia penfieldi Walcott, U. S. Geol. Surv. Mon. 2>2, pt. 2, p. 456, pi. 65, 

 figs. 4- 4b, 1899. 



Upper Cambrian ; south side Gallatin Valley, northwestern Yellow- 

 stone Park, Wyoming. 



Cotypes. — U.S.N.M. no. 35231. 



