386 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



of about 14 large granules on each thoracic segment and about lo or 

 less on each of the four anchylosed segments of the pygidium. 



The spine on the ninth thoracic segment has a strong base and is 

 extended back over the pygidium. 



There are tw^o specimens in the collection ; the larger has a length 

 of 23 mm. v^ith tv^o segments crowded under the cephalon, and the 

 other has lO thoracic segments and the pygidium. 



Formation and locality. — Upper Cambrian: (3011) Weeks forma- 

 tion; about 3,750 feet (1,143 ^O above the Lower Cambrian in 

 shales forming ic of the Weeks formation, on the north side of 

 Weeks Canyon, about 4 miles (6.4 km.) south of Marjum Pass, 

 House Range, Millard County, Utah. 



ASAPHISCUS IDDINGSI Walcott 



Plate 59, figs. I, la-b 



Asaphiscus iddingsi Walcott, 191 i, Smithsonian Misc. Coll., Vol. 57, No. 



4, PP- 99-101, pi. 16, fig. 3. (Described and discussed as a new species 



essentially as below.) 

 Asaphiscus iddingsi Walcott, 1913, Research in China, Vol. 3, Cambrian 



Faunas of China, p. 221, pi. 22, figs, i, la-b. (Described as below.) 



Dorsal shield longitudinally oval in outline, moderately convex. 

 Cephalon semicircular in outline ; a little more than one-third of the 

 entire length of the dorsal shield ; bordered by a nearly flat or slightly 

 rounded margin that passes at the genal angle into a moderately 

 strong genal spine ; within the genal spine a rounded posterior border 

 is separated from the fixed cheek by a rounded, clearly defined fur- 

 row ; the intramarginal furrow is shallow and rounded. Cranidium 

 moderately convex and roughly subquadrate in outline ; the frontal 

 limb is slightly convex and, with the anterior portion of the glabella 

 and the front margin, forms a gentle slope that is broken only by the 

 slight dorsal furrow in front of the glabella and the shallow intra- 

 marginal furrow ; the frontal limb merges on the sides into the fixed 

 cheeks, which are a little less than one-half the width of the glabella ; 

 posteriorly the fixed cheeks merge into relatively small postero-lateral 

 limbs ; palpebral lobe narrow and extended in front as a low ridge 

 that crosses the fixed cheek to the dorsal furrow near the antero- 

 lateral angle of the glabella; that portion of the palpebral lobe above 

 the eye is about one-fourth the length of the cephalon. 



Glabella large, slightly narrower in front than at the occipital 

 furrow ; sides nearly straight and slightly converging, frontal margin 

 broadly rounded ; surface marked by very faint impressions of three 



