808 PROCEEDINGS OF THE NATIONAL MUSEUM. voi.. xxvm. 



IC srulptilis Meek = I/>///'</d/((. 



K. Htissingensls D vv i ght = Tphidella. 



K. lohitfieldi W'A\co{i — BUUngseUa. 



KUTORGINA CINGULATA Billings. 



Oholella {KnlorgliKi) cliigulata Billincs, Geol. Vermont, H, ISfil, p. 94S, figs. 



347-349; Pal. Fohs., I, p. 8, figs. 8-10. 

 Oholelld. chrKjnlaia Bi lungs, Geol. Canada, 1S()3, ji. 284, fig. 287. 

 OholeUaf phUlipd Holl, Quart. Jour. Geol. Sor., XXI, 18(54, i>i». 101, 102, figs. 



10a, 1). 

 Kntorii'iiKi cingulata D.widson, (reel. Mag., V, 1868, p. 312, ])1. xvi, tig. 10; 



Brit. Hil. Brachiopoda, 1871, p. 342, i)l. l, fig. 25. 

 KuUmjina cliK/vlatd Walcott, Bull. V. S. Geol. Survey, 1886, p. 102, pi. ix, 



fig. 1. ^ 

 Kutorg'ma eingnlafa Beectier, Anier. Jour. Rei., 3d ser. , XLI, 1891, p. 345. 

 Kntorgina cingulata W.vlcott, Tenth A.nn. Rept. U. S. Geol. Survey, 1891, p. 



609, pi. Lxix, fig. 1. 

 Kutorg'ma cingulata II.vll and Clarke, Pal. Xew York, VIII, 1892, Pt. 1, p. 92, 



figs. 47-49; pi. iv, figs. 10-17. 

 Kutorg'ma cingulata von Toll, Mem. de I'Acad. Imp. des Sci. de St. Peters- 

 burg, VIII ser., 1899. I, Beit, zur Kenntniss des Siberischen Cambrium, p. 



26, pi. I, fig. 28. 



General form transversely or lonoitudinally oval; biconvex, with the 

 ventral much more convex than the dorsal valve. Surface marked by 

 concentric lines and ridges of growth and the edges by imbricating 

 lamella^ of growth. Shell substance calcareous and fibrous. The shell 

 is formed of a thin, dark, compact outer layer and a thick, fibrous, 

 calcareous inner layer. It is possible that the thin outer layer is chi- 

 tinous, but it does not appear to be so. The L'Anse au Loup and Bic 

 Harbor shells average about 15 mm. long by 17 mm. in width. At 

 the Swanton locality, in Vermont, ventral valves occur 24 mm. in 

 height and with a width of 30 mm., and one large dorsal valve is 20 

 mm, in length with a width of 30 mm. 



Ventral valve in young shells moderately convex, becoming more 

 and more convex with increase in size and age. In young shells the 

 slope from the front margin to the apex is nearly straight, and the 

 apex terminates at the posterior edge of the valve above the more or 

 less elevated pseudodeltidium. In old shells the curvature from the 

 front to the apex is nearly a semicircle, and the apex terminates in 

 a pointed beak overhanging the pseudodeltidium. A mesial sinus of 

 varying strength occurs on many shells, and in others it is entirely 

 absent. The pseudo area is concave on the outer parts. Toward the 

 center it becomes slightly flattened or convex and thus forms a very 

 rudimentary pseudodeltidium. It extends beneath the apex at an 

 angle of about 4.5° to the plane of the margins of the valve. The 

 central portion of the pseudo area extends about one-half the distance 

 from the apex to the plane of the valve and forms a gentle arch. 



A partially exfoliated shell shows four dark lines radiating forward 



