17 Essays in Paleontology and Stratigraphy FIG. 4. a, b, e, h, Pronorites sp., a, b, front and side views respectively, UCLA 39480, X2; e, h, side and ventral views, UCLA 39479, X2; c, d, Cravenoceras sp., front and side views, UCLA 39481, X2; /, j, L Liroceras liratum (Girty); /, oblique side and front views, UCLA 39478, X2; j, I, side and front views, UCLA 39477, XL; g, i, Syngastrioceras walk^eri Webster and Lane, n. sp., front and side views respectively, holotype, UCLA 39482, XL. Mississippian-Pennsylvanian in Nevada 519 The suture (Fig. 3, b, 3, c) has a trifid ventral lobe, a minimum of three lateral lobes, the first of which is bifid, and one umbilical lobe. All lobes are elongate and rounded in youthful stages; with maturity and proximity to the venter the lobes become more sharply pointed. The saddles are evenly rounded and extended adorally. On the larger specimen, the umbilical shoulder is not preserved; a fourth lateral lobe might have been present on the flank. No ornamentation was observed on fragmentary thin ferruginized shell material. Measurements (mm.) Hypotype 39479 Hypotype 39480 Diameter 18.7 Height of last whorl (H) 9.01 3.2 Width of last whorl (W) 8.01 3.6 Width of umbilicus (U) 5.3 Proportions U/D .28 W/D .19 W/H .89 1.12 Remarks.—Gordon (1965, p. 286) reported Pronorites as occurring in the United States in lower Chester rocks in Arkansas and Utah. Discovery of specimens at Apex extends the range into late Chester in southern Nevada. Material.—UCLA 39479 and 39480. Genus Syngastrioceras Librovich, 1938 Syngastrioceras and Glaphyrites were considered junior synonyms of Eoasianites by Miller, Furnish, and Schindewolf (1957). Gordon (1965) placed Syngastrioceras in synonymy with Glaphyrites, recognizing the latter, and assigning to Glaphyrites most of the American species previously assigned to Eoasianites. Syngastriceras has been reported from the Canadian Arctic by Nassichuk and Furnish (1965). McCaleb (personal communication) concurs with Miller, Furnish, and Schindewolf in considering Glaphyrites a synonym of Eoasianites but recognizes Syngastrioceras. He notes that Syngastrioceras may be distinguished from Eoasianites by differences in, and development of, the suture. Furthermore, Syngastrioceras is restricted to Upper Mississippian and Lower Pennsylvanian rocks, whereas Eoasianites ranges from Middle Pennsylvanian into Lower Permian. This is the first reported occurrence of Syngastrioceras from Upper Mississippian rocks in North America. Specimens identified as Eoasianites, though possibly belonging to Syngastrioceras, have been reported from the upper part of the Eumorphoceras bisulcatum Zone (EL>) in Spain (Wagner-Gentis, 1963) and in Yugoslavia (Kullman, 1962b). Syngastrioceras walkeri Webster & Lane, n. sp. Figs. 3, d; 4, g, i Description.—Conch unornamented with thin shell, subglobose, whorl height approximately one-fourth of width; venter wide, gently convex; umbilical shoulder sharp, forming an acute angle of 68°; umbilicus stepped, approximately three- 1 Measurements approximate. 520 Essays in Paleontology and Stratigraphy fourths of diameter of width of shell; umbilical walls moderately convex; suture (Fig. 3, d) with long sharply pointed lobes and slightly bulbous elongate first lateral saddles which converge adorally; first lateral lobes diverging slightly apicad; saddles evenly rounded. The outer whorl of the holotype has a broad, gently convex venter with a slight increase in convexity on the flanks. Measurements (mm.) : Holotype Paratype Diameter (D) 53.7 51.5 Height of last whorl (H) 10.1 9.0 Width of last whorl (W) 40.7 38.5 Width of umbilicus 37.9 35.3 Proportions: U/D .75 .69 W/D .76 .75 W/H 4.03 4.28 Remarks.—All specimens studied are distorted in varying degrees and enclosed in dense, finely crystalline limestone that had to be removed by chipping or grinding. Original shell material of all specimens has been replaced entirely or in part, by hematite. Only the holotype and paratypes, representing internal molds of phragmocones, were freed from matrix including one or both umbilical plugs. This species is most similar to S. globosus (Easton, 1943). It differs from the latter in having a much wider umbilicus, less convex venter, and more sharply pointed lobes. The species is named in honor of Mr. Lawrence Walker, who found the initial specimen. Types.—Holotype, UCLA 39482; Paratype, UCLA 39483. ACKNOWLEDGMENTS We wish to thank W. M. Furnish, State University of Iowa, J. A. McCaleb, Pai} American Petroleum Corp., and MacKenzie Gordon, Jr., United States Geological Survey, for advice concerning taxonomy of the cephalopods; C. B. Rexroad, Indiana Geological Survey, for confirmation of conodont identifications; MacKenzie Gordon, Jr., and Walter Sadlick, who read the manuscript; and Mrs. Peter Kurtz, University of California, Los Angeles, for drafting the text figures. Field work was supported by the Research Committee of the U.C.L.A. Academic Senate. REFERENCES Bissell, H. J., 1962, Pennsylvanian and Permian rocks of Cordilleran area, in Branson, C. C., ed., Pennsyl- vanian System in the United States: Tulsa, Oklahoma, Am. Assoc. Petroleum Geologists, p. 188- 263, 31 figs. Brill, K. G., Jr., 1963, Permo-Pennsylvanian stratigraphy of western Colorado Plateau and eastern Great Basin regions: Geol. Soc. America Bull., v. 74, p. 307-331, 17 text-figs., 1 pi. Mississippian-Pennsylvanian in Nevada 521 Coogan, A. 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Kl., Jahrg. 1962, no. 6, p. 261-377, 7 pis., 17 figs. , 1962b, Namirski dat druzetica i njegova gonijatitska fauna: Yugoslavia, Mus. Histoire Nat. Bull., Ser. A, livr. 16-17, p. 45-112, 4 pis., 7 figs. [Belgrad. Prirodnjackog muzeja, Glasnik]. Lane, N. G., 1961, An occurrence of Archimedes in southern Nevada: Jour. Paleontology, v. 35, p. 874- 875, 1 fig. , 1963, A silicified Morrowan brachiopod faunule from the Bird Spring Formation, southern Nevada: Jour. Paleontology, v. 37, p. 379-392, 6 figs., pis. 43-45. , 1964, New Pennsylvanian crinoids from Clark County, Nevada: Jour. Paleontology, v. 38, p. 677- 684, 1 fig., pi. 112. Langenheim, R. L., Jr., et al., 1962, Paleozoic section in Arrow Canyon Range, Clark County, Nevada: Am. Assoc. Petroleum Geologists Bull., v. 46, p. 592-609, 5 figs. Langenheim, V. A. M., and Langenheim, R. L., Jr., 1965, The Bird Spring Group, Chesterian through Wolfcampian, at Arrow Canyon, Arrow Canyon Range, Clark County, Nevada: Illinois State Acad. Sci. 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F., 1915, The fauna of the Morrow Group of Arkansas and Oklahoma: Denison Univ. Sci. Lab. Jour., v. 18, art. 3, p. 59-284, 16 pis. Miller, A. K., Furnish, W. M., and Schindewolf, O. H., 1957, Paleozoic Ammonoidea, in Part L, Mollusca 4, of Moore, R. C., ed., Treatise on Invertebrate Paleontology: Geol. Soc. America and Univ. Kansas Press, p. 11-79, 123 figs. Moore, R. C., et al., 1944, Correlation of Pennsylvanian formations of North America: Geol. Soc. America Bull., v. 55, p. 657-706. Nassichuk, W. W., and Furnish, W. M., 1965, Christioceras, a new Pennsylvanian ammonoid from the Canadian Arctic: Jour. Paleontology, v. 39, p. 724-728, 2 figs. Nolan, T. B., Merriam, C. W., and Williams, J. S-, 1956, The stratigraphic section in the vicinity of Eureka, Nevada: U.S.