NO. 2 CAMBRIAN AND LOWER OZARKIAN TRILOBITES 57 



axis of the pygidium. Pygidium with spines sometimes long and 

 slender, at other times with peculiar hook-like blunt ends. 

 Genotype. — E. granulosa, new species. 



Range. — Upper Cambrian, Great Basin, Rocky Mountains, Missis- 

 sippi A' alley. 



HARDYIA new genus 

 PI. 12, fig. 5. (X 2.) Outline drawing of type cranidium. 



Hardyia is a small trilobite with wide fixed cheeks, narrowing 

 rapidly forward, with large occipital ring and very short, faintly indi- 

 cated glabellar furrows. 



Genotype. — H. metion new species. 



Range. — Ozarkian. Canadian Rockies. 



HOLTERIA new genus 



PI. 13, fig. 7. (Nat. size.) Diagrammatic restoration of the cranidium and 

 pygidium of the type species. 



The genus Holteria is based primarily on the unusual pygidium. 

 The associated cranidium is indistinguishable generically from that 

 of Neolenus inflatiis Walcott. The pygidium, however, is radically 

 different because of the fusion of the pleura and the reduction of the 

 number of spines. 



Genotype. — Ogygia ? problcmafica Walcott (Mon. U. S. Geol. 

 Surv., 8, 1884, P- ^^3» pl- lO- %• 2). 



Range. — Upper Cambrian, Great Basin. 



HOUSIA (Walcott) 



PI. 12, fig. 4. (Nat. size.) Outline drawing of the type species. 



Housia was first described as a subgenus of DoUchometopus, due 

 to a portion of the specimen being obscured by the matrix and 

 thus overlooked in making the illustration. The generic name Sodalitia 

 (Smithsonian Misc. Coll., 67, 1922, p. 471) was proposed for forms 

 belonging to this genus. 



Housia is characterized by the absence of the dorsal furrow and 

 the large frontal limb. The pygidium of the British Columbia forms 

 was first referred to Ceratopyge because of the marginal spines. It 

 difi^ers, however, from Ceratopyge in that the spines of Housia are 

 simply the ends of a thoracic segment attached to the posterior smooth 

 portion of the pygidium. 



Genotype. — DoUchometopus (Housia) varro Walcott (Smithson- 

 ian Misc. Coll., 64, 1916, p. 374, pi. 65, fig. i). 



Range. — Ozarkian. British Columbia and Great Basin. 



