56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 75 



DUNDERBERGIA new genus 



PI. II, fig. 2. (Nat. size.) Outline drawings of cranidium and pygidium. 



Dunderbergia includes a number of forms which have formerly 

 been assigned to Ptychoparia (unrestricted). This genus is charac- 

 terized by the absence of glabellar furrows and the rounded, bordered 

 pygidium. It differs from Modocia in its narrower fixed cheeks and 

 the direction of the facial suture. 



Genotype.- — Crepicephalus (Loganellus) nitidus Hall and Whit- 

 field (Geol. Expl. 40th Parallel, vol. 4, 1877, p. 212, pi. 2, figs. 8-10). 



Range. — Upper Cambrian. Rocky Mountains and Basin Ranges. 



ELKIA new genus 



PL 10, fig. 8. (Nat. size.) Diagrammatic restoration of the cranidium. 



Elkia is characterized by the extended frontal rim and very narrow 

 fixed cheeks. The palpebral lobes appear to be considerably elevated. 

 Other parts of the trilobite unknown. 



Genotype.- — Dicellocephalns nasntus Walcott (Mon. U. S. Geol. 

 Surv., 8, 1884, p. 40, pi. 10, fig. 15). 



Range. — Upper Cambrian. Eureka District, Nevada. 



ELRATHIA new genus 



PI. II, fig. 4. (Nat. size.) Outline drawing of the type species. PI. 11, 

 fig. 5 (medium sized specimen) diagrammatic outline of Ptychoparia striata 

 (Corda), the type of the genus, introduced for comparison. 



Elrathia is erected to include many forms hitherto assigned to 

 Ptychoparia. It is characterized by the wide frontal limb, the wide 

 fixed cheeks and the large, flat, furrowed pygidium. 



Genotype. — Conocoryphe (Conocephalites) kingii Meek (Proc. 

 Acad, Nat. Sci. Philadelphia, 1870, p, 63). 



Range. — Middle Cambrian, mainly. Cordilleran area and possibly 



elsewhere, „.. „.^^^ . 



ELVINIA new genus 



PI. II, fig. 3. (Nat. size.) Restoration of cephalon and pygidium of the 



type species. 



Elvinia includes many species widely distributed, formerly referred 

 to Ptychoparia. This genus is characterized by the first pair of glabel- 

 lar furrows which distinguishes it from similar forms. 



Genotype.— Dikclocephalus roemcri Shumard (Amer. Jour. Sci., 

 2d ser., vol. 32, 1861, p. 220). 



Range. — Upper Cambrian and Ozarkian, New York, Pennsylvania, 

 and generally west of the Mississippi River, 



EUREKIA new genus 



PI. 12, fig. I. (Nat. size.) Diagrammatic restoration of the cephalon and 

 pygidium of the type species. 

 Eurekia is characterized by the upturned, frontal limb, the moder- 

 ately large eyes situated far back, narrow fixed cheeks and the high 



