70 SMITHSONIAN MISCELI^ANEOUS COLLECTIONS VOL. 53 



brian quartzitic sandstones and 1,050 feet (320 m.) below the Upper 

 Cambrian in thin-bedded limestones of the Bloomington formation 

 [Walcott, 19080, p. 7] ; and (7) about 2,100 feet (640.1 m.) above 

 the top of the Cambrian quartsitic sandstones and 2,090 feet (dj/ m.) 

 belozv the Upper Cambrian in the shales of the Bloomington forma- 

 tion; both about 8 miles (12.87 km.) above the mouth of Blacksmith 

 Fork, and 15 unties (24.14 km.) east of Hyrum, Cache County; all 

 in Utah. ' (8) About 2,000 feet (609.6 m.) above the Cambrian 

 quartzitic beds and 1,200 feet (365.8 m.) below the Upper Cambrian, 

 in the shales of the Bloomington formation, on the south side of 

 Two Mile Canyon near its mouth, 2 miles (3.22 km.) southeast of 

 Malad, Oneida County, Idaho. 



MICKWITZELLA, new subgenus of OBOLUS 



Obolus (Thysaiiotos) Mickwitz, 1S96, Mem. Acad. Imp. Sci., St. Peters- 

 bourg, 8th sen, IV, No. 2, pp. 194-195. (Characterized in German as 

 a new subgenus; see below for translation.) 



Obolus (Thysanotus) Mickwitz, Walcott, 1901, Proc. U. S. National 

 Museum, XXIII, p. 683. (Characterized.) 



Not Thysanota Alt., i860. 



Original Description by Mickwitz. — "The subgenus Thysa- 

 notos, containing a single species, 0. siluricus Eichwald, differs from 

 the Cambrian subgenera Buoboliis and Schmidtia mainly by the 

 fringed anterior border of the growth lamellae of its valves and by 

 the concentric striation arranged parallel to the posterior edge of 

 these lamellae — two features that point to a peculiar organization of 

 the edge of the mantle. The last-mentioned peculiarity appears also 

 in the subgenus Acritis." 



Type. — Obolus siluricus Eichwald [1843, P- 7]- 



Genus LINGULELLA Salter [18666, p. 333] 

 LINGULELLA BUTTSI, new species 



Plate 8, Figure 6 



General form elongate ovate, with the ventral valve bluntly acu- 

 minate and the dorsal valve a little more rounded on the posterior 

 margin ; both valves rather strongly convex. The greatest convexity 

 of the dorsal valve is at the umbo, and of the ventral valve along the 

 central section. A ventral valve 12 mm. in length has a convexity 

 of 2 mm., and a dorsal valve 8 mm. long arches 1.75 mm. above the 

 plane of the margin. A narrow, median, slightly flattened, almost 

 concave space, that extends from the apex to the front margin, 

 occurs on the dorsal valve. The exterior surface of the shell is dull 



