NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES QT 



HARDYIA METION Walcott 



Plate 1 8, fig. 9 



Hardyia metion Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, p. 57, 

 pi. 12, fig. 5. 



The illustration and generic description include the known specific 

 characters. 



Formation and locality. — Ozarkian : (66k) Mons formation. 

 Ranger Canyon, Sawback Range, Alberta. 



Genus HOLTERIA Walcott 



Holtcria Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, p. 57. 



Description. — The genus is based primarily on the pygidium. It 

 is fairly certain that the head and tail assigned to the genotype belong- 

 together, but the cranidia of Holteria problematica and of Neolenus 

 inf^atus ^ Walcott are indistinguishable generically while the pygidia 

 assigned to the two species are quite unlike. 



The cranidium is characterized by the large prominent glabella, 

 which expands toward the front. There is no frontal limb, thus 

 causing the glabella tO' occupy the full length of the cranidium, which 

 has three sets of very faint glabellar furrows ; the posterior pair 

 being broad and somewhat interrupted by small elevations within 

 them. 



Fixed cheeks narrow in front, widening out rapidly posteriorly, 

 due to the contracting glabella and the diverging suture. Eyes a 

 little less than medium size, situated about opposite the middle of 

 the glabella. The facial suture diverges somewhat in passing forward 

 from the eye leaving a flat area at the front corners ; it may possibly 

 be intramarginal, a point that cannot be determined in the absence of 

 a rim and since the free cheeks are unknown. At the point where the 

 margin of the glabella turns toward the front, there are pit-like 

 depressions, a character very prominent in some of the related genera. 

 Back of the eye the facial suture turns suddenly outward outlining 

 rather long and broad postero-lateral limbs. 



The pygidium is very distinctive. It is broad and flat with a well- 

 defined axis extending more than three-fourths of the distance to 

 the posterior margin. The axis is relatively narrow and tapers to a 

 slight broadening at the end. The five axial furrows are not deep and 

 the posterior ones are barely discernible. 



'See Ncolcnns, 1908, Smithsonian Misc. Coll. Vol. 53, No. 2, pis. 4-6. 

 3 



