OBOLID^. 573 



p. 3], 8 miles (12.8 km.) northeast of Shipleys, near tlie line between the Roan Mountain and Bristol quadrangles (U. S. 

 Geol. Siirvey); all in Sullivan County, Tennessee. 



(103a) Upper part of the second shale south of the ridge of sandstone in the Rome formation ("Town Knobs"), on 

 the road fi-om Rogersville to Dodson Ford, near the line between the Morristown and Greeneville quadrangles (U. S. 

 Geol. Survey); (102) Rogersville shale just south of road, one-half mile (0.8 km.) southwest of Rogersville, on the 

 road to Melinda Ferry [Keith, 1896a, areal geology sheet]; (104) shale in railroad cut 0.5 mile (0.8 km.) from Rogers- 

 ville on the road to Holston River, near the line between the Morristown and Greeneville quadrangles (U. S. Geol. 

 Survey); (124a) shale (Nolichucky?) overlying the limestone which rests on the Rogersville shale, on Big Creek, 

 southeast of Harlan Knob, 4 miles (6.4 km.) northeast of Rogersville [see Keith, 1905, p. 4, and areal geology sheet]; 

 and (374b) shale 1.25 miles (2 km.) from Rogersville, near the line between the Morristown and Greeneville 

 quadrangles (U. S. Geol. Survey); all in Hawkins County, Tennessee. 



(107) Limestone in Bull Run; and (107b) shales in railroad cut in Bull Run; both northwest of Copper Ridge 

 [Keith, 1896b, areal geology sheet], 11 miles (17.6 km.) northwest of Knoxville, Knox County, Tennessee. 



(11a) Sandstone between First and Armstrong creeks, in the southeast corner of the Maynardville quadrangle 

 (U. S. Geol. Survey), Union County; (117c) shale at Buckingham Ford on Hollis Creek, 5 miles (8 km.) south- 

 east of Greeneville, Greene County; (374a) limestones 2 miles (3.2 km.) south of Coal Creek, Anderson County; 

 and (119) limestone in various localities in Jefferson and Hawkins counties; all in Tennessee. 



(16) Conasauga limestone, Blountsvilfe Valley, Blount County; (89) limestone in Murphrees Valley, Blount 

 County; (90a) shales at Cedar Bluff, Cherokee County; (90b) Conasauga limestone, in cut on Louisville and Nash- 

 ville Raih'oad, near Woodstock, Bibb County; (144c) limestone near the top of the beds exposed nearN. K. Burns's 

 barns, near Swansea (Viola), Blount County; and (91) Conasauga ("Coosa") shale, at Cedar Bluff, Cherokee County; 

 all in Alabama. 



(471i) Shales on Wolf Creek, 6 miles (9.6 km.) below Rocky Gap, Bland County, Virginia. 



DicELLOMUs NANUS (Meek and Hayden). 

 Plate LIII, figures 1, la-1, 2, 2a, 3, 3a-d. 



Obolella nana Meek and Hayden, 1862, Proc. Acad. Nat. Sci. Philadelphia for 1861, vol. 13, pp. 435-436. (Described 

 and discussed as a new species.) 



Obolella nana Meek and Hayden, Hayden, 1862, Am. Jour. Sci., 2d ser., vol. 33, p. 73, figs, la-b and 2a-b. (Char- 

 acterized and discussed. The two specimens represented by figs. 2a and 2b are redrawn in this monograph, 

 PL LIII, figs. 2a and 2, respectively.) 



Obolella nana Meek and Hayden, Billings, 1862, Geol. Survey Canada, Paleozoic Fossils, vol. 1, pp. 67-68. (Original 

 reference, Meek and Hayden, 1862, pp. 435-^36, copied.) 



Obolella nana Meek and Hayden, 1865, Smithsonian Contrib. Knowl., No. 172, Paleontology Upper Missouri, pt. 1, 

 p. 4, PL I, figs. 3a-d. (Described and discussed. Figs. 3a-b and 3c-d are copied from Hayden, 1862, p. 73, 

 figs. 2a and 2b, respectively.) 



Obolella nana Meek and Hayden, Whitfield, 1880, U. S. Geog. and Geol. Survey Rocky Mtn. Region, Rept. Geology 

 and Resources Black Hills of Dakota, by Newton and Jenney, pp. 340-341, PL II, figs. 14-17. (Copies the 

 description given by Meek and Hayden, 1865, p. 4, and discusses species. Fig. 17 is copied from Meek and 

 Hayden, 1865, PL I, fig. 3d.) 



Obolella nana Meek and Hayden, Walcott, 1886, Bull. U. S. Geol. Survey No. 30, p. 111. (Discussed.) 



Obolella nana Meek and Hayden, Hall and Claeke, 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, pp. 69-70. 

 (Discussed.) 



Dicellomus nanus (Meek and Hayden), Walcott (in part), 1899, Mon. U. S. Geol. Survey, vol. 32, pt. 2, p. 447, PL 

 LX, figs. 3a-d (not fig. 3). (Synonymy and new localities given. Figs. 3b and 3d are drawn from the specimens 

 figured by Hayden, 1862, p. 73, figs. 2a and 2b, and are redrawn in this monograph, PL LIII, figs. 2a and 2, 

 respectively. The specimens represented by figs. 3a and 3c are not figured in this monograph. The specimen 

 represented by fig. 3 is referred in this monograph to Lingulella desiderata.) 



Dicellomus nanus (Meek and Hayden), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, pp. 314-315. (Described and 

 discussed essentially as below.) 



The principal characters of this species are the same as Dicellomus politus (Hall). The 

 two forms differ exteriorly in D. nanus being more convex on the umbones and less elongate. 

 The interior of the ventral valve shows a less elongate visceral area, a relatively larger com- 

 posite muscle scar (cl) ; the interior of the dorsal valve of D. nanus has a much larger com- 

 posite muscle scar and a broader visceral area with the central muscle scar farther from the 

 median line. 



One of the types of D. nanus is the interior of a ventral valve (PL LIII, fig. 2), on which 

 there is a subtriangular depression (c) that appears to have been the path of advance of the 

 areas, on each side of the median space, in which the central muscle, and the middle and outside 



