Siemans ) SIG 5 WASHINGTON GOVERNMENT PRINTING OFFICE Oe? Ve UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director CAMBRIAN BRACHIOPODA _ BY CHARLES D. WALCOTT Part 1--PwAT ES WASHINGTON GOVERNMENT PRINTING OFFICE 1912 ; i me oR 7 aA eae tae F PLATE I. a. Area. s. Median septum (see fig. 47A, p. 567). cl. Cardinal scars. t. Ridges mentioned in the text (see fig. h. Central muscle scar. 47A, p. 567). j. Anterior lateral muscle scars. t’. Depressed cardinal area (see fig. 47A n. Cast of short ridge in advance of apex. p. 567). p. Pedicle furrow. v. Visceral area. RustEeL_La EDsONI Walcott (p. 327). Ficures 1 and la. Casts of the exterior of compressed ventral valves from Locality 25, Lower Cambrian, Georgia, Vermont. U.S. Nat. Mus. Cat. Nos. 51412a and 51412b, respectively. Specimens represented by figs. 1 and la were figured by Walcott [1886b, Pl. IX, figs. 1h and Ig, respectively; and 1891a, Pl. LXIX, figs. 1h and lg, respectively] as ventral valves of Kutorgina cingulata. Figure 1 is the type. 1b. Cast of the interior of a ventral valve from Locality 49a, Lower Cambrian, York, Pennsylvania. U.S. Nat. Mus. Cat. No. 51463a. 1c. Cast of the interior of a ventral valve from Locality 25, Lower Cambrian, Georgia, Vermont. U.S. Nat. Mus. Cat. No. 51412c. 1d and le. Casts of the exterior of dorsal valves from Locality 3920, Vermont. U.S. Nat. Mus. Cat. Nos. 52035a and 52035b, respectively. CURTICIA ELEGANTULA Walcott (p. 369). Ficures 2, 2’, 2”. Top and back views and side outline of the exterior of a ventral valve, the type specinen. U.S. Nat. Mus. Cat. No. 51902a. 2a, 2a’, 2a/’. Top, side, and back views of a more nearly circular ventral valve than that represented by fig. 2. U.S. Nat. Mus. Cat. No. 51902b. ; 2b. Top and side views of a ventral valve. U.S. Nat. Mus. Cat. No. 51902c. 2c. Partly exfoliated ventral valve showing inner layers of the shell. U.S. Nat. Mus. Cat. No. 51902d. 2d. Posterior view of an elevated ventral valve having a large delthyrium. U.S. Nat. Mus. Cat. No, 51902e. 2e. Posterior view of a ventral valve with very low delthyrium. U.S. Nat. Mus. Cat. No. 519028. 2f. Back view of the cast of a ventral valve. U.S. Nat. Mus. Cat. No. 51902g. 2g. Posterior portion of the cast of a ventral valve. U.S. Nat. Mus. Cat. No. 51902h. 2h, 2i, and 2j. Exterior of dorsal valves and side outlines. U.S. Nat. Mus. Cat. Nos. 51902i, 51902j, and 51902k, respectively. 2k. Interior of a dorsal valve with a trace of muscle scars near the apex. U.S. Nat. Mus. Cat. No. 51902 1. 21. Cast of the interior of a dorsal valve, retaining a portion of the shell. U.S. Nat. Mus. Cat. No. 51902m. Another specimen (Cat. No. 51902n) was used also in drawing fig. 21. The specimens represented are all from Locality 82b, Upper Cambrian, ‘‘St. Croix sandstone,” Taylors Falls, Chisago County, Minnesota. Nrosotus wartut Waagen (p. 566). [Text figs. 47A-B, p. 567, and Pl. LXXXI, figs. 2, 2a-h.] Ficure 3. This specimen is figured by Waagen [1885, Pl. LXXXIV, fig. 7; and 1891, Pl. II, fig. 8c] as the interior of a dorsal valve of Neobolus warthi. “It may possibly be an old shell, worn by rolling in the sand. Geol. Survey India Cat. No. 3/779. 4 and 4’. Exterior and back views of a specimen of the ventral valve. Geol. Survey India Cat. No. 3/776. Specimen figured by Waagen [1885, Pl. LX XXIV, fig. 4; and 1891, Pl. II, fig. 5] as Neobolus warthi. 4a. Specimen of the dorsal valve. Geol. Survey India Cat. No. 3/777. Specimen figured by Waagen [1885, Pl. LXXXIV, figs. 5a-b; and 1891, Pl. II, figs. 8a=b] as Neobolus warthi. 4b. This figure, which is diagrammatic and incorrect, is replaced by text figure 47A, p.567. Interior of a dorsal valve from a cast made in a natural mold. Original in the collection of the Geological Survey of India (Cat. No. 3/780); cast in the United States National Museum (Cat. No. 56909a). 5. Ventral valve described and illustrated by Waagen [1885, p. 759, Pl. LXXXYV, figs. la-c; and 1891, Pl. II, figs. 1la—b] as Neobolus wynnei. Geol. Survey India Cat. No. 3/781. 5a. Dorsal valve described and illustrated by Waagen [1885, p. 759, Pl. LXXXYV, figs. 2a-c; and 1891, Pl. II, figs. 10a-b] as Neobolus wynnei. Geol. Survey India Cat. No. 3/782. All the specimens from which the above figures of Neobolus warthi are drawn are from Locality 357c, the Neobolus beds of the Khussak group of the Middle Cambrian, Kiura, Salt Range, India. 6 we U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. HELIOTYPE CO SOSTON MONOGRAPH LI Biel PLATE I. v6 SCHIZOPHOLIS RUGOSA Waagen (p. 609). [Pl. LXXXT, figs. 1, la-c.] Fieure 4c. Interior of a dorsal valve from a cast made in a natural mold. The casts were obtained first by dissolving the shells and then taking wax and plaster casts of the uninjured natural molds. From Locality 357c, the Neobolus beds of the Khussak group of the Middle Cambrian, Kiura, Salt, Range, India. Original in the collection of the Geological Survey of India (Cat. No. 3/780); cast in the United States National Museum (Cat. No. 56910a). VOLBORTHIA RECURVA (Kutorga) (p. 366). [Text figs. 33A-B, p. 366.] Freures 6, 6a, 6b, 6c, and 6d. Posterior, side, front, ventral, and dorsal views of the type specimen, a partly exfoliated shell which has the two valves united, from Locality 336g, Ordovician glauconitic lime- stone at Zarskoe Selo, Government of St. Petersburg, Russia. 6e. View of the false area of the ventral valve represented in figs. 6, 6a-d. The false area of this shell has been illustrated by photography in text figs. 33A and 33B, p. 366. Figures 6, 6a-e are copied from von Moller [1874, Pl. VII, figs. 1-6, respectively]. Original specimen in the col- lection of the Museum at Reval, Esthonia, Russia; cast in the United States National Museum (Cat. No. 58298). Se eeEee CL ae Dr ee AS me i? SU Aighian Malet im ites ; miley eons eR Sune ; Raat) AG ae ee $F ays PLATE II. Micromirra (PATERINA) BELLA (Billimgs) (p. 344). Ficure 1. Apical, posterior, and side views of a ventral valve. U.S. Nat. Mus. Cat. No. 51417a. Until the speci- men represented by fig. lc is found this valve may be regarded as typical of the species. (See pp. 335 ‘and 350 and fig. 6 of this plate.) la. Summit, posterior, and side views of a dorsal valve. U.S. Nat. Mus. Cat. No. 51417b. 1b. Dorsal valve, showing a somewhat more elevated beak than in figure la. U.S. Nat. Mus. Cat. No. 51417c. The specimens represented by figures 1, la-b are all from Locality 49w, Lower Cambrian limestone one-fourth mile south of Emigsville, York County, Pennsylvania. Ficure le. Type specimen, from Locality 2n, Lower Cambrian limestone bowldersin conglomerate at Trois Pistoles, Quebec. Copied from Billings [1872b, fig. 18, p. 477]. The figure has been widely copied (see p. 344), but the specimen from which it was drawn can not be located. (See pp. 335 and 350 and fig. 6 of this plate.) Micromirra (PATERINA) LABRADORICA (Billings) (p. 347). Ficure 2. Enlarged drawing of the type specimen, from Locality 392a, Lower Cambrian at L’Anse au Loup, Straits of Belleisle, Labrador. Geol. Survey Canada. Specimen originally figured by Billings [1861h, fig. 6, p. 6]. 2a. Dorsal valve. U.S. Nat. Mus. Cat. No. 18309a. Specimen figured by Walcott [189la, Pl. LXIX, fig. 3b] as Kutorgina labradorica. 2b. Posterior view of a small ventral valve. U.S. Nat. Mus. Cat. No. 18309b. 2c. Partly exfoliated shell of a ventral valve. U.S. Nat. Mus. Cat. No. 18309c. Specimen figured by Walcott [1891a, Pl. LXTX, fig. 3a] as Kutorgina labradorica. 2d. A more elevated ventral valve, which has been partly broken away along the cardinal margin. U.S. Nat. Mus. Cat. No. 18309d. Specimen figured by Walcott [1891a, Pl. LXIX, fig. 3] as Kutorgina labradorica. The specimens represented by figures 2a-d are from Locality 41a, Lower Cambrian limestone at Topsail Head, Conception Bay, Newfoundland. Frcure 2e. Dorsal valve from Locality 3a, Lower Cambrian shale on Hanford Brook, St. J ohn County, New Bruns- wick, Canada. U.S. Nat. Mus. Cat. No. 51428a. 2f. Ventral valve associated with specimen represented by figure 2e. U.S. Nat. Mus. Cat. No. 51428b. Mrcromirra (PATERINA) LABRADORICA SWANTONENSIS (Walcott) (p. 348). Ficure 3. Apical view and side outline of a ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 15329a. 3a. Apical view and side outline of a more elevated ventral valve. U.S. Nat. Mus. Cat. No. 15329b. 3b. Dorsal valve associated in the same block of limestone with the specimen represented by figure 3a. U.S. Nat. Mus. Cat. No. 15329c. The specimens represented by figures 3, 3a—b were figured by Walcott [1886b, Pl. IX, figs. 2, 2a-b, respectively] as Kutorgina labradorica, and [1891a, Pl. LXIX, figs. 2, 2a-b, respectively] as Kutorgina labradorica swantonensis. Ficure 3c. Longitudinal section of a ventral valye showing the presence of a short pseudodeltidium. U.S. Nat. Mus. Cat. No. 15329d. The specimens represented by figures 3, 3a-c are all from Locality 25a, Lower Cambrian limestones, 2 miles east of Swanton, Franklin County, Vermont. Ficures 3d, 3e, and 3f. Apical, side, and posterior views of a specimen preserving the area and pseudodeltidium. This specimen can not be located. The drawing was labeled as having been made from a specimen in the collections of the American Museum of Natural History, but the officials inform me that they have no record of such a specimen. The locality is unknown. Mrcromirra (PATERINA) PROSPECTENSIS (Walcott) (p. 352). Ficure 4. Apical view of the type specimen, a ventral valve, from Locality 52, Lower Cambrian sandy shales, summit of Prospect Mountain, Eureka district, Nevada. 4a. Dorsal valve associated with the ventral valve represented by figure 4. The specimens represented by figures 4 and 4a were figured by Walcott [1884b, Pl. TX, figs. la and 1, respectively; 1886b, Pl. IX, figs. 3 and 3a, respectively; and 1891a, Pl. LXIX, figs. 4 and 4a, respectively] as Kutorgina prospectensis. U.S. Nat. Mus. Cat. Nos. 15335a and 15335b, respectively. 10 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. I! FRANCES WIESER DEL. HELIOTYPE CO. BOSTON fi 7 ' te PLATE II. wl MicroMITRA ALABAMAENSIS (Walcott) (p. 337). Figure 5. Apical view of the type specimen, a compressed ventral valve, from Locality 121, Middle Cambrian Rogers- ville shale, 4 miles northeast of Rogersville, Tennessee. U.S. Nat. Mus. Cat. No. 51416a. Speci- men figured by Walcott [1897b, Pl. LIX, fig. 5] as [phidea alabamaensis. 5a. Dorsal valve from Locality 94a, Middle Cambrian Conasauga shale, Coosa Valley, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 56888a. Specimen figured by Walcott [1897b, Pl. LIX, fig. 5a] as Iphidea alabamaensis. ‘ 5b. Ventral valve having a slight median depression, from Locality 14a, Middle Cambrian Rogersville shale, 4 miles north-northeast of Knoxville, Knox County, Tennessee. U.S. Nat. Mus. Cat. No. 51418a. 5c. Outer surface of shell from Locality 94, Middle Cambrian Conasauga shale, Cowan Creek section, Cherokee County, Alabama, enlarged to show the tendency to form crenulations in the strie. U.S. Nat. Mus. Cat. No. 26432a. This bit of surface was figured by Walcott [1897b, Pl. LIX, fig. 5b] as part of the surface of figure 5, magnified; it is, however, taken from another specimen. Micromitra (PATERINA) LOGANI (Walcott) (p. 350). Ficures 6, 6a, and 6b. Apical, side, and posterior views of the type specimen, from Locality 2n, Lower Cambrian pebbles in conglomerate at Trois Pistoles, on the St. Lawrence, Province of Quebec, Canada. Coll. Geol. Survey Canada. Specimen figured by Walcott [1897b, Pl. LIX, figs. 2, 2a—-b] as Iphidea logani. In the Canadian Survey collections it was labeled as the type of ‘Iphidea bella Billings.”’ (See pp. 345 and 350 and figs. 1 and 1c of this plate.) Micromirra (PATERINA) SUPERBA (Walcott) (p. 355). [Text figs. 27A-B, p. 355.] Figures 7, 7a, and 7b. Apical, side, and posterior views of the type specimen, a ventral valve, from Locality 73a, Middle Cambrian sandy ‘‘Tonto” shale, Chuar Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 264292. Specimen figured by Walcott [1897b, Pl. LIX, figs. la—c] as [phidea superba. : 7c. Specimen of the dorsal valve associated with the specimen represented by figure 7. U.S. Nat. Mus. Cat. No. 26429b. Specimen figured by Walcott [1897b, Pl. LIX, fig. 1] as Iphidea swperba. 7d. Nearly perfect dorsal valve from Locality 74, Middle Cambrian sandy ‘‘Tonto” shale at head of Nunko- weap Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 51487a. ; Ze. Posterior view of ventral valve, from Locality 8j, Middle Cambrian shale, near Gordon Mountain, Ovando quadrangle, Montana, showing pseudodeltidium. U.S. Nat. Mus. Cat. No. 51488a. 7f. A crushed and broken ventral valve, associated with the valve represented by figure 7e, showing pseudo- deltidium. U.S. Nat. Mus. Cat. No. 51488b. MicroMItrA (PATERINA) LABRADORICA UTAHENSIS (Walcott) (p. 349). [Text fig. 24, p. 350.] ; Ficures § and 8’. Summit and side views of the type specimen, a ventral valve laterally compressed. U.S. Nat. Mus. Cat. No. 51431a. 8a. Posterior half of a ventral valve somewhat distorted by compression. U.S. Nat. Mus. Cat. No. 51431b. The specimens represented are both from Locality 34, Middle Cambrian, Oquirrh Range, near Ophir, Utah. WIMANELLA SHELBYENSIS Walcott (p. 747). Figure 9. Type specimen, the ventral valve, flattened in the shale. Copied from Walcott [1908d, Pl. X, fig. 3]. 9a. Interior of a flattened dorsal valve. The specimens represented are both from Locality 17b, Lower Cambrian Rome (‘‘Montevallo”’) formation, 4 miles south of Helena, Shelby County, Alabama. U.S. Nat. Mus. Cat. Nos. 52272a and 52272b, respectively. MicromMitra (PATERINA) WILLIARDI Walcott (p. 358). [Text figs. 30A-E, p. 358.] Ficures 9b and 9c. Side outlines of ventral valves. Drawn from casts taken in a natural mold from Locality 17b, Lower Cambrian Rome (‘‘Montevallo”) formation, 4 miles south of Helena, Shelby County, Alabama. U.S. Nat. Mus. Cat. Nos. 5148la and 51481b, respectively. Micromitra Nisus (Walcott) (p. 338). Ficure 10. Exterior of type specimen, ventral valve, from Locality 2r, Lower Cambrian, 2 miles west of Bic, Province of Quebec, Canada, showing radiating ridges. U.S. Nat. Mus. Cat. No. 51440a. Micromitra (PATERINA) LABRADORICA ORIENTALIS (Walcott) (p. 348). Figure 11. Exterior of type specimen, dorsal valve, from Locality C9, Middle Cambrian limestone, Kiulung group, 3 miles southwest of Yenchuang, Sintai district, Shantung, China. U.S. Nat. Mus. Cat. No. 52516a. Lat ee Fe. * a ee 5 ? 7 , f ¢ \ . . : { g = nS “ ' i i 4 : ' as . 1 a 7% i iG PLATE III. Micromirra (PATERINA) STISSINGENSIS (Dwight) (p. 353). Figure 1. Apical view of the type specimen, a ventral valve. U.S. Nat. Mus. Cat. No. 51484a. Specimen figured by Dwight [1889, Pl. VI, fig. 6] as Kutorgina stissingensis. ja. Dorsal valve, flattened in the shale. U.S. Nat. Mus. Cat. No. 51484b. The rear view of this specimen was given by Dwight [1889, Pl. VI, fig. 8]. 1b. Apical view of a cast in limestone of a ventral valve. U.S. Nat. Mus. Cat. No, 51484c. 1c. Interior of a typical specimen of a compressed dorsal valve. U.S. Nat. Mus. Cat No. 51484d. Specimen figured by Dwight [1889, Pl. VI, fig. 5] as Kutorgina stissingensis. 1d. Posterior view of a compressed ventral valve that shows the area of a narrow pseudodeltidium. The specimens represented by figures 1, la-d are from Locality 367d, Middle Cambrian, vicinity of Stissing, Dutchess County, New York. Fiaure le. Specimen doubtfully referred to this species from Locality 14s, Middle Cambrian, Ogygopsis zone, Mount Stephen, British Columbia. U.S. Nat. Mus. Cat. No. 51483a. z Micromirra PUSILLA (Linnarsson) (p. 339). Ficures 2 and 2a. Apical and posterior views of a ventral valve. U.S. Nat. Mus. Cat. No. 51478a. 2b and 2b’. Top and side views of a ventral valve. U.S. Nat. Mus. Cat. No. 51478b. 2c. Exterior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51478c. The specimens represented are all from Locality 8w, Middle Cambrian limestones near Andrarum, Sweden. Micromirra PEALEI (Walcott) (p. 339). FraurEs 3, 3a, and 3b. Apical, side, and posterior views of the type specimen, from Locality 155a, Middle Cambrian limestone near Hillsdale, Montana. U.S. Nat. Mus. Cat. No. 26430a. Specimen figured by Walcott [1897b, Pl. LIX, figs. 3, 3a-b] as Iphidea pealet. 3c. Dorsal valve from the same bed of limestone as the ventral valve represented by figure 3. U.S. Nat. Mus. Cat. No. 26430b. Specimen figured by Walcott [1897b, Pl. LIX, fig. 3c] as Iphidea pealet. 3d. Ventral valve with strong radiating ridges, from Locality 159, Middle Cambrian limestone, north of West Gallatin (Gallatin) River, Montana. U.S. Nat. Mus. Cat. No. 51471a. 3e and 3e’. Top and back views of a transverse dorsal valve with strong radiating ridges, from Locality 5f, Middle Cambrian limestone, 12 miles south of Neihart, Montana. U.S. Nat. Mus. Cat. No. 51470a. Micromitra (PATERINA) CRENISTRIA (Walcott) (p. 345). Figures 4, 4a, and 4b. Apical, side, and posterior views of the type specimen, from Locality 74, Middle Cambrian limestone, Tonto group, near the head of Nunkoweap Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 2643la. . Specimen figured by Walcott [1897b, Pl. LIX, figs. 4, 4a-b] as Iphidea crenistria. Mricromirra scuupTitis (Meek) (p. 341). Fieures 5, 5’, and 5’. Apical, side, and posterior views of the type specimen, from Locality 302, Middle Cambrian limestone east of West Gallatin (Gallatin) River, Montana. U.S. Nat. Mus. Cat. No. 7864a. Speci- men figured by Walcott [1884b, Pl. I, figs. 7, 7a] as Kutorgina sculptilis. " 5a, 5a’, and 5a’’. Top, side, and back views of a ventral valve from Locality 302b, Middle Cambrian lime- stones near Crowfoot Ridge, Yellowstone National Park, Wyoming. U.S. Nat. Mus. Cat. No. 35212a. Specimen figured by Walcott [1899, Pl. LX, figs. 5, 5a-c]. A portion of its surface is enlarged in figure 5e. 5b. Dorsal valve from Locality 58, Middle Cambrian Secret Canyon shale, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 2455la. Specimen figured by Hall and Whitfield [1877, Pl. I, fig. 11] as Kutorgina minutissima; and by Walcott [1884b, Pl. I, fig. 7b] as Kutorgina sculptilis. 5e. Dorsal valve associated with the shell represented by fig. 5b. U.S. Nat. Mus. Cat. No. 24551b. Specimen figured by Hall and Whitfield [1877, Pl. I, fig. 12] as Kutorgina minutissima; and by Walcott [1884b, Pl. IX, fig. 7] as Kutorgina sculptilis. 14 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. Ill ae 9) yy WN) r y Downe 5a eS 5 ae Car oem. a \\ i ») NK ya) y NR M SANG i HN WW) Noy it Aint pana avis ms t FRANCES WIESER DEL. HELIOTYPE CO BOSTON 5 i] ) b : . » 7 mies. Wei { PLATE III. 15 MiIcROMITRA SCULPTILIS (Meek)—Continued. Fieure 5d. Crushed ventral valve from Locality 8i, Middle Cambrian shaly Marjum limestone near Antelope Springs, House Range, Utah. U.S. Nat. Mus. Cat. No. 51494a. 5e. A portion of the surface of the specimen represented by figure 5a, greatly enlarged. U.S. Nat. Mus. Cat. No. 35212a. Mrcromirra (IPpHIDELLA) ORNATELLA (Linnarsson) (p. 360). Fiaures 6, 6a, and 6b. Apical, side, and posterior views of a typical specimen from Locality 320f, Middle Cambrian limestone at Andrarum, Sweden. U.S. Nat. Mus. Cat. No. 26667a. 6c. Dorsal valve from Locality 8w, Middle Cambrian limestone near Andrarum, Sweden. U.S. Nat. Mus. Cat. No. 51460a. : 6d. Interior of a dorsal valve from Locality 16h, Middle Cambrian shale at Borregaard, Bornholm, Denmark, U.S. Nat. Mus. Cat. No. 51490a. Mrcromirra sp. undt. (Walcott) (p. 343). FreureE 7. Dorsal valve from Locality 302b, Middle Cambrian limestones near Crowfoot Ridge, Yellowstone National Park, Wyoming. U.S. Nat. Mus. Cat. No. 51509a. Specimen figured by Walcott [1899, Pl. LX, fig. 6] as ‘‘Iphidea, sp. undet.” Micromirra (PATERINA) PHILLIPSI (Holl) (p. 351). Figure 8. Top view of dorsal valve and side outline of valves from Locality 304g, Upper Cambrian Hollybush sand- stones, Malvern Hills, England. Copied from Davidson [1866, Pl. IV, figs. 17a and 17c]; Davidson’s figures were drawn from the type specimen illustrated by Holl [1865, p. 102, figs. 10b and 10c]. Mrcromirra (IpHIDELLA) NyssA Walcott (p. 360). Fiaure 9. Top view of type specimen, a ventral valve. Copied from Walcott [1908d, Pl. VII, fig. 5]. 9a. Top view of dorsal valve. The specimens represented are both from Locality 4q, Middle Cambrian shale, near Gordon Mountain, Ovando quadrangle, Montana. U.S. Nat. Mus. Cat. Nos. 51441a and 51441b, respectively. Micromirra (PATERINA) ETHERIDGE! (Tate) (p. 346). Figure 10. Top view of type specimen, a ventral valve from Locality 315, Middle Cambrian at Curramulka, South Australia. Original in the collection of the University of Adelaide, South Australia; cast in the United States National Museum (Cat. No. 58301). Specimen figured by Tate [1892, Pl. II, figs. 7a-c] as Platyceras etheridget. 10a and 10b. Side and back views of ventral valve represented in figure 10. Original in the collection of the University of Adelaide; cast in the United States National Museum (Cat. No. 58301). 10c. Back view of another ventral valve from the same locality as the valve represented by figure 10. Original in the collection of the University of Adelaide; cast in the United States National Museum (Cat. No. 58302). 5 ATW Beye. 62667°—vot 51, pr 2—12——2 yf PLATE IV. Micromitra (I[PHIDELLA) PANNULA (White) (p. 361). [Text fig. 32, p. 362, and P1. IV, figs. 3 and 3a.]} Fiaures 1 and la. Apical and side views of a ventral valve from Locality 74, Middle Cambrian ‘‘Tonto” sandstone Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 51446a. lb. Dorsal valve from Locality 149a, Middle Cambrian limestone on Pole Creek, Madison County, Montana. U.S. Nat. Mus. Cat. No. 51445b. lc. Dorsal valve from Locality 14, Middle Cambrian limestone 7 miles southwest of Rome, Floyd County, Georgia. U.S. Nat. Mus. Cat. No. 51444c. id and le. Posterior and side views of ventral valve from Locality 30, Lower Cambrian limestones near Pioche, Nevada. U.S. Nat. Mus. Cat. No. 51452a. Copied from Walcott [1908c, Pl. I, figs. 1b and la, respectively.] The figures were there wrongly placed as the posterior and side views of the specimen represented by figure Ir of this plate. The latter specimen occurs in British Columbia; the one represented by figures 1d and le occurs in Nevada. lf. Posterior view of the dorsal valve represented in figure 1b, showing the characters described in the text (see p. 362). U.S. Nat. Mus. Cat. No. 51445b. lg. Drawing of the type specimen of the species. Locality 31a, Lower Cambrian siliceous shale near Pioche, Nevada. U.S. Nat. Mus. Cat. No. 1533la. Specimen figured by White [1877, Pl. I, figs. 4a and 4b] as Trematis pannula; and by Walcott [1886b, Pl. VII, figs. 3 and 3a; and 189la, Pl. LXIX, fig. 5d] as Kutorgina pannula. The surface is enlarged in figure 1o of this plate. 1h and li. Apical and posterior views of a dorsal (?) valve from Locality 78a, Middle Cambrian “‘Tonto” ‘sandstone, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 51447a. The surface is enlarged in figure In of this plate. i Jj and 11. Apical and side views of a small specimen from Locality 31a, Lower Cambrian limestone near Pioche, Nevada. U.S. Nat. Mus. Cat. No. 15333a. Specimen figured by Walcott [1886b, Pl. VIII, figs. 2 and 2a; 1891a, Pl. LXIX, figs. 5 and 5a] as Kutorgina pannula. 1k. Dorsal valve from same locality as the specimens represented by figures 1j and 11. U.S. Nat. Mus. Cat. No. 15333b. Specimen figured by Walcott [1886b, Pl. VIII, figs. 2b and 2c; 1887, Pl. I, fig. 14b; and 189la, Pl. LXIX, figs. 5b and 5e] as Kutorgina pannula. The outer surface is enlarged in figure Ip of this plate. Im. Ventral valve from Locality 38a, Lower Cambrian limestones near North Granville, Washington County, New York. U.S. Nat. Mus. Cat. No. 17442a. Specimen figured by Walcott [1887, Pl. I, figs. 14 and 14a; and 1891a, Pl. LXIX, figs. 5¢ and 5f] as Kutorgina pannula. The outer surface is enlarged in figure 1q of this plate. In. Enlargement of a portion of the outer surface of the specimen represented by figure 1h. lo. Enlargement of a portion of the outer surface of the type specimen, figure 1g. ip. Enlargement of a portion of the outer surface of the specimen represented by figure 1k. Figured by Walcott [189la, Pl. LXTIX, fig. 5e] as the surface of the specimen represented by figure 1m; and [1887, Pl. I, fig. 14b; and 188Gb, Pl. VIII, fig. 2c] as the outer surface of 1k. lq. Enlargement of a portion of the outer surface of the dorsal valve represented by figure 1m. Figured by Walcott [189la, Pl. LXTX, fig. 5f] as the surface of the valve represented by figure 1k; and [1887, Pl. I, fig. 14a] as the outer surface of 1m. Ventral valve from Locality 14s, Middle Cambrian Ogygopsis zone on Mount Stephen, British Columbia. Coll. Mr. Byron E. Walker, Toronto, Canada., Copied from Walcott [1908c, Pl. I, fig. 1]; see note under figures Id and le. 1s. Enlargement by photography of a ventral valve from Locality 74, Middle Cambrian “‘Tonto” sandstone, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 51446b. 1t. Enlargement by photography of a ventral valve from Locality 149a, Middle Cambrian limestones on Pole Creek, Madison County, Montana. U.S. Nat. Mus. Cat. No. 51445a. dr. 4 Micromitra (IPHIDELLA) PANNULA MALADENSIS (Walcott) (p. 364). Figure 2. Exterior of ventral valve from Locality 5b, Middle Cambrian limestone, 2 miles southeast of Malade, Idaho, showing pitting of surface, and obscure, radiating ridges. U.S. Nat. Mus. Cat. No. 51468a. 2a. Apical view of ventral valve associated with valve represented by figure 2. U.S. Nat. Mus. Cat. No. 51468b. 18 PL MONOGRAPH GEOLOGICAL SURVEY Uh Ss 2 NJ Sue Mi ' wee FRANCES WIESER DEL, LIOTYPE CO BOSTON HE PLATE IV. 19 Micromitra (IPHIDELLA) PANNULA MALADENSIS (Walcott)—Continued. Figures 2a/ and 2a’. Side and back views of specimen represented by figure 2a, illustrating the area and pseudodel- tidium. 2b, 2b’, and 2b’. Apical, back, and side views of an elevated ventral valve from Locality 6g, Middle Cam- brian limestone, Chapple Arm, Trinity Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 6406e. 4690 2e. Apical view of an elevated, laterally compressed ventral valve associated with the valve represented by figure 2b. U.S. Nat. Mus. Cat. No. 51469b. 2d and 2e. Exterior of two dorsal valves from Locality 5b, Middle Cambrian limestone, 2 miles southeast of Malade, Idaho, with the same type of surface as the specimen represented by figure 2. U.S. Nat. Mus. Cat. Nos. 51468¢ and 51468d, respectively. Figure 2e represents the type specimen. 2f. Partly exfoliated, transverse dorsal valve from locality 6g, Middle Cambrian limestone, Chapple Arm, Trinity Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51469c. 2¢. Enlargement of a portion of the surface near the center of a ventral valve from Locality 5b, Middle Cam- brian limestone, 2 miles southeast of Malade, Idaho, that has (on its frontal portion) a surface like that represented by figure 4c of the variety ophirensis. U.S. Nat. Mus. Cat. No. 51468e. Mrcromitra ([purpELtaA) PANNULA (White) (p. 361). [Text fig. 32, p. 362, and Pl. IV, figs. 1, 1a-t.] 9 Ficure 3. Posterior portion of a ventral valve having a very fine surface of the type represented by figure 1q. 3a and 3a’. Apical and side views of a ventral valve associated with the specimen represented by figure 3. The specimens represented are both from Locality 14, Middle Cambrian limestone, 7 miles southwest of Rome, Ployd County, Georgia. U.S. Nat. Mus. Cat. Nos. 51444a and 51444b, respectively. Mrcromitra ([PHIDELLA) PANNULA OPHIRENSIS (Walcott) (p. 365). Fiaures 4and 4’. Apical and side views ofa ventral valve. U.S. Nat. Mus. Cat. No. 51464a. da, 4a’, and 4a’’. Apical, back, and side views of a ventral valve, the type specimen, in which the beak slightly overhangs the posterior margin. U.S. Nat. Mus. Cat. No. 51464b. (See fig. 4c.) 4b. Exterior of a dorsal valve with very fine, undulating, concentric strie. U.S. Nat. Mus. Cat. No. 51464c. 4c. Enlargement of a portion of the specimen represented by figure 4a, to illustrate irregular and inoscu- lating strie. U.S. Nat. Mus. Cat. No. 51464b. 4d and 4d’. Top and back views of a transverse dorsal valve. U.S. Nat. Mus. Cat. No. 51464d. 4e. Partly exfoliated dorsal valve, showing the cast of a median septum and the position of the central muscle scars. U.S. Nat. Mus. Cat. No. 51464e. 4f. A small, convex dorsal valve. U.S. Nat. Mus. Cat. No.51464f. The specimens represented are all from Locality 3e, Middle Cambrian limestone, Oquirrh Range, near Ophir, Utah. ie * =) wee v Bh Ee Ace: PLATE V. a. Pseudo-area. p. Pedicle opening. h, Central muscle scar. s. Median septum. j. Anterior lateral muscle scar. vy. Visceral area. vs. Main vascular sinus. KurorGina crIncuLATA (Billings) (p. 580). (Text figs. 3, p. 299, 8, p. 299, and 50A-C, p. 581.] Ficure 1. Top and side view of a partly exfoliated ventral valve from Locality 25a, Lower Cambrian limestone, 2 miles east of Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15337a. Specimen figured by Walcott [1886b, Pl. IX, fig. 1d; and 189la, Pl. LXIX, fig. 1d]. la. Side view of the two valves united, from Locality 25a, near Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15337b. Specimen figured by Walcott [1886b, Pl. IX, fig. 1c; and 189la, Pl. LXIX, fig. 1c]. 1b 1c, and 1d. Side, ventral, and dorsal views of a nearly entire shell, natural size, from Locality 26a, near Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15337d. Specimen figured by Walcott [1886b, Pl. IX, figs. 1, la-b; and 1891la, Pl. LXIX, figs. 1, la-b]. Je and 1f. Side and dorsal views of a younger shell than that represented by figures 1b, 1c, and 1d, but from the same locality. U.S. Nat. Mus. Cat. No. 15336a. lg. Exfoliated dorsal valve, showing central muscle scars and radiating vascular canals. From Locality 392a, Lower Cambrian limestones at L’Anse au Loup, Labrador. U.S. Nat. Mus. Cat. No. 14893a. th. Interior of a dorsal valve from Locality 2a, Lower Cambrian limestone, 2 miles east of Swanton, Vermont, showing muscle scars and vascular canals. U.S. Nat. Mus. Cat. No. 15337c. Specimen figured by Walcott [1886b, Pl. IX, fig. 1f; and 189la, Pl. LXIX, fig. 1]. li. Exterior of a dorsal valve from Locality 25a, Lower Cambrian, 2 miles cast of Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15337f. Specimen figured by Walcott [1886b, Pl. LX, fig. le; and 1891a, Pl. LXTX, fig. le]. 1j. Exterior and side views of a fine ventral valve from Locality 20, Lower Cambrian limestone, Bic Harbor, Province of Quebec, Canada. U.S. Nat. Mus. Cat. No. 51510a. 1k and 1k’. View of area and side view of a ventral valve from Bic Harbor (Locality 20). U.S. Nat. Mus. Cat. No. 51510b. 1land 1m. Exterior views of two dorsal valves from Bic Harbor (Locality 20). U.S. Nat. Mus. Cat. Nos. 51510c and 51510d, respectively. In. View of pseudo-area beneath apex of an elevated ventral valve from Locality 25a, Lower Cambrian lime- stone, 2 miles east of Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15336b. lo. Transverse section of the two valves in natural position, from Swanton, Vermont (Locality 25a). The gaping ; pedicle opening is’ well shown. U.S. Nat. Mus. Cat. No. 15336c. lp. Enlargement of a cross section of a fragment of the shell from Locality 25a, Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15337e. 1q. Enlargement of a longitudinal section of the shell at the apex of the ventral valve. Locality 26a, Lower Cambrian, 2 miles east of Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15336d. Irand Is. Exterior of ventral and dorsal valves from Locality 392a, Lower Cambrian limestone at L’Anse au Loup, Straits of Belleisle, Labrador, Canada. U. S. Nat. Mus. Cat. Nos. 14893b and 14893c, respectively. . KurorGina PECULIARIS (Tate) (p. 583). Figure 2. Top view of type specimen, a dorsal valve, from Locality 31a, Middle? Cambrian, at Ardrossan, Yorke Peninsula, South Australia. Original in the collection of the University of Adelaide, Adelaide, South Australia. Cast in the United States National Museum (Cat. No. 58300). Spetimen figured by Tate [1892, Pl. II, fig. 5] as Orthis (?) peculiaris. Kuroreina PERUGATA Walcott (p. 583). Figure 3. Exterior and side view of an exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 5151la. The outline of the visceral area is drawn from another specimen. U.S. Nat. Mus. Cat. No. 51511g. 3a. Top and side views of a less elongate ventral valve than that represented by figure 3. U.S. Nat. Mus. Cat. No. 51511b. 22 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. FRANCES WIESER DEL. i HELIOTYPE CO BOSTON PLATE V. 40 KurorGina PERUGATA Walcott—Continued. Ficure 3b. Exterior, side, and back views of a dorsal valve. The pseudo-area is broken away. U.S. Nat. Mus. Cat. No. 51511c. 3c. Top, back, and side views of an exfoliated dorsal valve, the type specimen, showing pseudo-area. U.S. Nat. Mus. Cat. No, 51511d. 3d. Exterior of dorsal valve illustrating variation in the concentric corrugations. U.S. Nat. Mus. Cat. No. 5151 le. 3e. Small, strongly corrugated ventral valve, drawn from the cast of a natural mold. U.S. Nat. Mus. Cat. No. 51511. The specimens represented are all from Locality 1v, Lower Cambrian, Silver Peak quadrangle (U. 8. Geol. Sur- vey), Nevada. KurorGIna SARDINIAENSIS Walcott (p. 584). Figure 4. Ventral valve, the type specimen, from Locality 354e, Middle ? Cambrian, Sardinia. Copied from Borne- mann [1891, Pl. XIX, fig. 21], who describes and figures the specimen as Lingula roualti. 4a. Exterior of ventral valve from Locality 354e, Middle? Cambrian shale at Porto Canal Grande, Sardinia. U.S. Nat. Mus. Cat. No. 18301a. 4b and 4c. Exteriors of dorsal valves from Locality 354e, Middle ? Cambrian, Sardinia. Copied from Borne- mann [1891, Pl. XIX, figs. 22 and 23, respectively], who describes and figures them as Kutorgina cingulata. KKXUTORGINA GRANULATA Matthew (p. 582). Ficures 5 and 5a. Top and side views of a broken ventral valve. Type specimen figured by Matthew [1899a, Pl. I, fig. 2a]; it is redrawn on this plate. 5b. Partly exfoliated interior of a dorsal valve. Specimen figured by Matthew [1899a, Pl. I, fig. 2c]; it is redrawn on this plate. 5c. Partly exfoliated exterior of a dorsal valve. Specimen figured by Matthew [1899a, PI. I, fig. 2b]; it is redrawn on this plate. The specimens represented are all from Locality 314b, Lower Cambrian limestone, Smith Sound, Newfoundland, and are in the collection of the University of Toronto, Canada. Pn Te LM, Y tiie vioweeananrae EE Vale MICKWITZIA MONILIFERA (Linnarsson) (p. 330). [Pl. LIX, fig. 2.] Ircures 1, 1’, and 1’. Top, side, and back views of a partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 51520a. la. Top and side views of a small ventral valve. U.S. Nat. Mus. Cat. No. 51520b. 1b. Exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 51520c. le. Interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51520d. + 1d. Interior of a dorsal valve, showing a trace of the path of advance of the posterior lateral muscle scars. U.S. Nat. Mus. Cat. No. 51520e. le. Posterior view ofa dorsal valve, showing the arching of the margin. The apex of the valve is broken ap U.S. Nat. Mus. Cat. No. 51520f. 1f. Interior of a worn dorsal valve, showing indications of a median depression and the path of advance of fixe posterior lateral scars. U.S. Nat. Mus. Cat. No. 51520g. lg, 1h, li, and 1j. Ventral, dorsal, side, and back views of a cast of the two valves, the dorsal valve having been crushed inward. U.S. Nat. Mus. Cat. No. 238938a. 1k. Surface of an inner lamellation or layer of shell magnified six times. U.S. Nat. Mus. Cat. No. 51520h. 11. Surface of an inner layer of shell magnified about five times. This isa character illustrated by Linnarsson [1896b, Pl. XI, fig. 2]. U.S. Nat. Mus. Cat. No. 515201. Im. Exterior layer of shell, reenali worn so as to show sections of the papille and puncte. The papillee when unworn are elevated and have a minute opening at the apex (see fig. In). U.S. Nat. Mus. Cat. No, 51520). In. Exterior papillose surface of a shell, greatly magnified. U.S. Nat. Mus. Cat. No. 51520k. The specimens represented by figures 1, la—n are all from Locality 390j, Lower Cambrian Hophyton sandstone at Lugnas, Province of Skaraborg, Sweden. Fiaures lo and 1p. Side and back views of a cast of a compressed and somewhat distorted ventral valve from Locality 396r, Lower Cambrian, at Streitberg, near Reval. Esthonia, Russia. Copied from Schmidt, 1888, Pl. II, figures 12c and 12d, respectively. Mickwirzra pretioss Walcott (p. 332). Fiaure 2. Top view of the type specimen from Locality 390j, Lower Cambrian Eophyton sandstone at Lugnas, Province of Skaraborg, Sweden. U.S. Nat. Mus. Cat. No. 51523a. Copied from Walcott [1908d, Pl. VII, fig. 2]. f Micxwirzia rormosa (Wiman) (p. 329). Figures 3, 3a, and 3b. Top, side, and posterior views of the type specimen from Locality 3111, Middle? Cambrian, sandstone on the peninsula of Biludden, Gefle Bay, Sweden. Original in the collection of the Univer- sity of Upsala; cast in the United States National Museum (Cat. No. 58299). 3c. Enlargement of a portion of the surface of one of the inner layers of the shell represented in figure 3, the epidermal layer having probably been exfoliated. The specimen represented was figured by Wiman [1902, Pl. II, figs. 1-5]as Causea formosa. Mickwirzia occiwens Walcott (p. 331). Ficure 4. Type specimen, from Locality 174c, Lower Cambrian shale, Silver Peak quadrangle (U.S. Geol. Survey), Nevada, showing outer and inner surfaces of the outer layer. U.S. Nat. Mus. Cat. No, 51518a. 4’. Side outline of specimen represented by figure 4. Figures 4 and 4’ are copied from Walcott [1908d, Pl. VII, figs. 1 and 1/]. 26 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. VI FRANCES WIESER DEL, HELIOTYPE CO BOSTON ee AKL Gen ur eat M75 Je ibya Ns) WUE. PLATE VII. a. Central lateral space of area. k. Middle lateral muscle scar. a’. Outer lateral space of area. 1. Outside lateral muscle scar. f{. Flexure line of area. p. Pedicle groove. g. Umbonal muscle scar. vs. Main vascular sinus. h. Central muscle scar. x. Heart-shaped cavity. i. Transmedian muscle scar. x’. A slight depression of the bottom of the . j. Anterior lateral muscle scar. heart-shaped cavity. Oxsotus APOLLINIS Eichwald (p. 381). [Text figs. 4, p. 299, and 15, p. 299, and Pl. XIV, figs. 6, 6a.) Figures 1-6. Interiors of ventral valves illustrating variations in size, form, and position of the central, middle lateral, and outside lateral muscle scars. From Locality 94, Upper Cambrian Obolus sandstone, at Jaggowal, east of Reval, Esthonia, Russia. U.8&. Nat. Mus. Cat. Nos. 51524a-t, respectively. 7 and 8. Interiors of ventral valves from Locality 395b, Upper Cambrian Obolus sandstone, at Ilgast, Esthonia, Russia, showing variation in form and arrangement of the muscle scars, central depression, ete. U.S. Nat. Mus. Cat. Nos. 51525a and 51525b, respectively. 10, 11, and 12. Interiors of ventral valves from Locality 94, Upper Cambrian Obolus sandstone, at Jaggowal, Esthonia, Russia, showing variation in the form and arrangement of the muscle scars, central depres- sion, etc. U.S. Nat. Mus. Cat. Nos. 35238a, 35238b, and 35238c, respectively. Specimens figured by Walcott [1898b, Pl. X XVI, figs. 3-5, respectively]. 3 13. Fragment of the interior of a ventral valve from Locality 94, Upper Cambrian Obolus sandstone, at Jaggo- wal, Esthonia, Russia, in which the heart-shaped cavity is nearly lost, and in which the centrals, middle laterals, and outside laterals are crowded into a narrow space. The drawing of the central and outside lateral scars is smewhat conventionalized. U.S. Nat. Mus. Cat. No. 35238d. Specimen figured by Walcott [1898b, Pl. XX VI, fig. 6]. 14, 15, 16, and 17. Interiors and posterior portions of dorsal valves from Locality 395b, Upper Cambrian Obolus sandstone, at Ilgast, Esthonia, Russia, showing the variation in position of muscle scars. U.S. Nat. Mus. Cat. Nos. 51525c-f, respectively. OBOLUS APOLLINIS MAXIMUS Mickwitz (p. 384). [Pl. XIV, figs. 7 and 7a.] Ficure 9. Interior of a ventral valve in which the thickening of the shell is very great. From Locality 395, Upper Cambrian Obolus sandstone, at Joa, near Jegelecht, Esthonia, Russia. U.S. Nat. Mus. Cat. No. 51528a. ; 28 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. Vil FRANCES WIESER OEL, HELIOTYPE CO BOSTON el AS, sy cae PLATE VIII. a. Central lateral space of area. o’. Overlapping of lines of growth of area. a’. Outer lateral space of area. p. Pedicle groove. ce. Trapezoidal area, including central, middle pvs. Peripheral branches of the vascular system. lateral, and outside lateral muscle scars. ps. Parietal band. f. Flexure line of area. s. Median septum. h. Central muscle scar. v. Visceral cavity. i. Transmedian muscle scar. vs. Main vascular sinus. j. Anterior lateral muscle scar. ivs. Lateral branches of vascular system. k. Middle lateral muscle scar. x. Heart-shaped cavity. 1. Outside lateral muscle scar. OBOLUS MATINALIS (Hall) (p. 400). I'ieure 1. Exterior of an almost perfect ventral valve from Locality 328e, a Middle Cambrian horizon in the ‘‘St. Croix sandstone,” St. Croix Falls, Wisconsin. U.S. Nat. Mus. Cat. No. 51564a. la. Large, partly exfoliated ventral valve from Locality 67¢, Upper Cambrian sandstone, Tatur Hill, Burnet County, Texas, showing the radial striation of the inner layers of the shell. U.S. Nat. Mus. Cat. No. * 52420a. Jb. Partly exfoliated ventral. valve from Locality 67, Upper Cambrian sandstone, Tatur Hill, Burnet County, Texas: U.S. Nat. Mus. Cat. No. 52419a. le. Partly exfoliated ventral valve associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 51564b. 1d. Cast of the interior of a ventral valve showing the details of the interior of the shell with unusual clear- ness, from Locality 82b, Upper Cambrian “‘St. Croix sandstone,’”’ Taylors Falls, Chisago County, Minnesota. U.S. Nat. Mus. Cat. No. 51563a. le. Cast of the interior of a ventral valve associated with the valve represented by figure 1. U.S. Nat. Mus. Cat. No. 51564c. y lf. Interior of a broken ventral valve from Locality 339d, Upper Cambrian ‘‘St. Croix sandstone” at Taylors Falls, Minnesota, showing the thickened shell under the visceral area. U.S. Nat. Mus. Cat. No. 51563c¢. lg. Interior of a ventral valve, in which there is no special thickening beneath the visceral area, associated with the specimen represented by figure lf. U.S. Nat. Mus. Cat. No. 51563d. th. Cast of the interior of a dorsal valve associated with the specimen represented by figure 1d. U.S. Nat. Mus. Cat. No. 51563b. li. Cast of the interior of a dorsal valve associated with the valve represented by figures 1, lc, and le. U.S. Nat. Mus. Cat. No. 51564d. 1j. Interior of a ventral valve in which there has been a considerable thickening of the shell so as to form a platform to which the muscles and visceral parts were attached. From Locality 339d, Upper Cam- brian “‘St. Croix sandstone,” Taylors Falls, Minnesota. U.S. Nat. Mus. Cat. No. 51563e. 1k. Partly exfoliated dorsal valve from Locality 71, Upper Cambrien limestone, Cold Creek Canyon, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 51566a, OBOLUS TETONENSIS NINUS Walcott (p. 418). [Pl. XI, figs. 1, la-g.] Figure 11. Ventral valve, showing the strongly marked radiating strie of the inner layers. 1m. Cast of the interior of a ventral valve. , In. Cast of the interior of a dorsal valve. lo. Cast of the interior of a partly exfoliated dorsal valve. The specimens represented by figures 11 to lo are from Locality 68, Upper Cambrian sandstone, Packsaddle Moun- fain, Llano County, Texas. U.S. Nat. Mus. Cat. Nos. 51644a-d, respectively. OsBoLus NAMoUNA Walcott (p. 406). Figure 2. Cast of the interior of a ventral valve, the type specimen, associated on the same hand specimen with the shells of Obolus rhea represented by figures la and 1b, Plate IX, from Locality 98, Upper Cambrian “St. Croix sandstone,” Eau Claire, Wisconsin. U.S. Nat. Mus. Cat. No. 27304a. 30 PL. Vill MONOGRAPH LI GEOLOGICAL SURVEY (Bi, Ss FRANCES WIESER DEL. BOSTON co HELIOTYPE PLATE VIII. 31 OsoLus NAMOUNA Walcott—Continued. Figure 2a. Cast of the interior of a dorsal valve associated on the same hand specimen with the specimen represented by figure 2. The remarkable feature of this specimen is the continuation of the lines of growth of the area far forward on the shell. U.S. Nat. Mus. Cat. No. 27304b. OBOLUS MATINALIS (Hall)? Walcott (p. 402). Figures 3 and 3a. Ventral and dorsal valves of partly exfoliated shells from Locality €54, Upper Cambrian Chau- mitien limestone, two-thirds mile west of Tsinan, Shantung, China. U.S. Nat. Mus. Cat. Nos. 52533a and 52533b, respectively. Jedbweci UR ID, 62667°—vou 51, pr 2—12 3 33 PLATE IX. a. Central lateral space of area. j. Anterior lateral muscle scar. a’. Outer lateral space of area. p. Pedicle groove. e. Trapezoidal area, including central, middle ps. Parietal band. lateral, and outside lateral muscle scars. y. Visceral cavity. {. Flexure line of area. vs. Main vascular sinus. h. Central muscle sear. x. Heart-shaped cavity. OBoLus RHEA Walcott (p. 410). Figure 1. Cast of the interior of a ventral valve, the type specimen, from Locality 98, Upper Cambrian “St. Croix sandstone,’ Eau Claire, Wisconsin, which shows the median, pestle-shaped ridge that filled the corresponding groove on the interior of the shell. Casts of the lines of growth and the visceral area are also finely preserved. U.S. Nat. Mus. Cat. No. 27300a. la. Cast of the interior of a ventral valve from Locality 98, Upper Cambrian ‘“‘St. Croix sandstone,”? Eau Claire, Wisconsin, in which some of the details of the anterior part of the visceral cavity are more clearly defined than in the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 27300b. lb. A dorsal valve, associated on the same hand specimen with the specimen represented by figure la, from which the shell has been almost wholly exfoliated. U.S. Nat. Mus. Cat. No. 27300c. The specimensrepresented in figures la and 1b are on the same slab of sandstone as the two specimens of Obolus namouna represented by figures 2 and 2a, Plate VIII. Figure lc. Cast of the interior of a dorsal valve from Locality 84, a Middle Cambrian horizon in the “‘St. Croix sand- stone,”? Dresbach, Minnesota, showing the area and traces of the vascular markings. U.S. Nat. Mus. Cat. No. 52430a. OBOLUS REFULGENS Matthew (p. 409). Ficure 2. Cast of the interior of a ventral valve, the type specimen, that is flattened in the shale. University of Toronto, Canada. Redrawn from the specimen figured by Matthew [1892, Pl. XII, fig. 6d (ventral)] as Obolus refulgens; and copied by him [1903, Pl. XI, fig. 4a] as Monobolina refulgens. 2a. Cast of the interior of a dorsal valve that preserves the original convexity. University of Toronto, Canada. Redrawn from the specimen figured by Matthew [1892, Pl. XII, fig. 6d (dorsal)] as Obolus refulgens; and copied by him [1903, Pl. XI, fig. 4b] as Monobolina refulgens. 2b. Veniral valve flattened in the shale and compressed laterally so as to give it more the outline of Lingulella than of Obolus. University of Toronto, Canada. 2c and 2d. Dorsal valves flattened in the shale and slightly distorted. University of Toronto, Canada. The specimens represented all occur in Locality 308, Upper Cambrian, Division 3c of Matthew, Navy Island, St. John Harbor, New Brunswick. Specimens represented by figures 2 and 2a occur in an arenaceous shale which preserves the specimens in better condition than in the argillaceous shales. OpoLtus PANDEMIA Walcott (p. 407). Figure 3. Exterior of a slightly flattened and distorted ventral valve. U.S. Nat. Mus. Cat. No. 27301a. 3a. Cast of the interior of a ventral valve, the type specimen, that has been compressed in its-posterior portion so as to force the visceral cavity back nearly to the area. U.S. Nat. Mus. Cat. No. 27301b. 3b. Interior of the ventral valve showing an elevated pestle-shaped median ridge that occupies the place of . the heart-shaped cavity of most species of Obolus. U.S. Nat. Mus. Cat. No. 27301c. 3c. Cast of the interior of a dorsal valve, showing the area. U.S. Nat. Mus. Cat. No. 27301d. 3d. Cast showing part of the interior of a dorsal valve, showing traces of the central muscle scars, and the thick lamination of the shell toward the margin. U.S. Nat. Mus. Cat. No. 27301e. The specimens represented are all from Locality 10a, Middle Cambrian, Bays Mountains, Knoxville, Tennessee. OxsoLus LOPERI Walcott (p. 395). Figure 4. Imperfect ventral valve from Locality 335a, Cambro-Ordovician sandstone, Cement Creek, 3 miles north of Hot Springs, Ouray County, Colorado, showing the general form and the several layers forming the shell. U.S. Nat. Mus. Cat. No. 27303a. 4a. Partly exfoliated dorsal valve, the type specimen, associated with the specimen represented by figure 4. U.S. Nat. Mus. Cat. No. 27303b. 34 U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. IX ee ZEN 5a FRANCES WIESER DEL. HELIOTYPE CO BOSTON PLATE IX. 3D Oxpoius TETONENSIS Walcott (p. 417). Fieure 5. A ventral valve, the type specimen, with the anterior portion of the shell exfoliated, from Locality 4e, Middle Cambrian limestone, Teton Mountains, Wyoming. U.S. Nat. Mus. Cat. No. 51639a. 5a. Dorsal valve associated with specimen represented by figure 5. U.S. Nat. Mus. Cat. No. 51639b. 5b. Outline of the two valves, showing their convexity. Drawn from specimen associated with specimens represented by figures 5 and 5a. U.S. Nat. Mus. Cat. No. 51639c. 5c. A small ventral valve from Locality 4m, Middle Cambrian sandstone in the Teton Mountains, Wyoming. U.S. Nat. Mus. Cat. No. 35220a. 5d. Dorsal valve associated with specimen represented by figure 5c. This shell may belong to some other species. U.S. Nat. Mus. Cat. No. 35220b. OBoLuS WorRTHENT Walcott (p. 421). {Text figs. 39A-D, p. 421.] Figure 5e. A very finely preserved interior of a small dorsal valve, the type specimen, from Locality 54u, Middle Cambrian limestone, 2 miles southeast of Malade, Idaho. U.S. Nat. Mus. Cat. No. 51638a. Copied from Walcott [1908d, Pl. VII, fig. 17]. Teiebe a ah es Jey, OX, PLATH X. c, Trapezoidal area, including central, middle s. Median septum. lateral, and outside lateral muscle sears. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. j. Anterior lateral muscle scar. x. Heart-shaped cavity. OxpoLus mioKwirzi Walcott (p. 403). Traure 1. Cast of asmall ventral valve, the type specimen, showing the deeply impressed vascular and visceral mark- ings. It will be noted that the visceral cavity extends far forward. U.S. Nat. Mus. Cat. No. 27299a. la. Cast of the interior of a ventral valve in which the visceral cavity is much larger proportionally than that represented in figure 1, and in which the areas occupied by the central, middle lateral, and outside lateral scars are unusually large and prominent. More than two-thirds of the entire length of the shell is taken up by the visceral area. U.S. Nat. Mus. Cat. No. 27299b. 1b. Portion of the cast of a small ventral valve in which the interior markings have been still more deeply impressed than in the specimens shown by figures 1 and la. The heart-shaped cavity (x), the trape- zoidal area (c), and the main vascular sinus (vs) must have been placed upon a strongly built up platform in the interior of the shell. U.S. Nat. Mus. Cat. No. 27299c. le. Cast of the interior of a large ventral valve in which the visceral area is limited to the posterior half of the shell. U.S. Nat. Mus. Cat. No. 27299d. 1d. Cast of the interior of a large dorsal valve which shows the relative position of the central (h) and anterior lateral (j) muscle scars, and the form of the visceral cavity. U.S. Nat. Mus. Cat. No. 27299e. le. Partly exfoliated: dorsal valve which illustrates the lamellated character of the sheil and the strong concentric undulations of growth which appear on some specimens. U. S. Nat. Mus. Cat. No. 272998. 1f. Cast of a large dorsal valve in which the visceral area is mainly upon the posterior half, as in the ventral valve represented by figure le. U.S. Nat. Mus. Cat. No. 27299¢. lg. Cast of the interior of a small dorsal valve in which the visceral area occupies the central portion of the shell. U.S. Nat. Mus. Cat. No. 27299h. th. Cast of the interior of a dorsal valve showing a remarkable development of the area about the central muscle scars. U.S. Nat. Mus. Cat. No. 27299i. li. Cast of the interior of a ventral valve in which the main vascular sinus and other interior markings of the shell are less deeply impressed than in specimens represented by figures la and 1b. The specimens represented in figures 1, la-i are from Locality 79, Upper Cambrian sandstone, at Hudson, Wis- consin. Frieure 1j. Cast of a ventral valve which is somewhat doubtfully referred to this species, owing to its not showing the same strong interior markings. This, however, may be the result of the condition of preservation. U.S. Nat. Mus. Cat. No. 56937a. 1k. Partly exfoliated dorsal valve associated with the specimen represented by figure 1j. It is probable that a larger collection of material would show that figures 1j and 1k represent a distinct species. U.S. Nat. Mus. Cat. No. 56937b. The specimens represented in figures 1j and 1k are from Locality 79b, Upper Cambrian sandstone at Hudson, Wisconsin, a slightly different horizon than the one containing the specimens represented in figures 1, la-i. Opotus M&RA (Hall and Whitfield) (p. 399). Ficure 2. Partly exfoliated and broken ventral valve from’ Locality 313j, Upper Cambrian limestone, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 24552a. 2a. Partly exfoliated dorsal valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 24552b. Type specimen figured by Hall and Whitfield [1877, Pl. I, fig. 6]as Lingulepis mera. 2b. More élongated, partly exfoliated dorsal valve from Locality 313j, Upper Cambrian limestone, Eureka district, Nevada. U. S. Nat. Mus. Cat. No. 24552c. Specimen figured by Hall and Whitfield (1877, Pl. I, fig. 5) as Lingulepis mexra. 2c. Crushed and partly exfoliated ventral valve, doubtfully referred to this species, from Locality 205, limestone forming passage beds between the Upper Cambrian and the Ordovician, on Roundtop Mountain, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 51562a. o> Lo 2) U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. X FRANCES WIESER DEL, HELIOTYPE CO BOSTON Tint ate te PLATE X. 39 OxsoLus MHRA (Hall and Whitfield)—Continued. Figure 2d. Exfoliated ventral valve from Locality 61, Upper Cambrian Dunderberg shale, south of the Hamburg ; mine, Eureka district, Nevada, showing outline of visceral area. U.S. Nat. Mus. Cat. No. 5156la. 2e. Partly exfoliated ventral valve, showing radial striation of interior layers of the shell, Locality 58, Middle Cambrian Secret Canyon shale, New York and Secret canyons, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 51560a. Oxsoius ANcCEPS Walcott (p. 380). Ficure 3. Partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 27302a. 3a. Partly exfoliated ventral valve showing the area. U.S. Nat. Mus. Cat. No. 27302b. 3b. Cast of the interior of a dorsal valve, the type specimen, showing the area and traces of the vascular markings. U.S. Nat. Mus. Cat. No. 27302c. 3c. More elongated dorsal valve than that represented by figure 3b. U.S. Nat. Mus. Cat. No. 27302d. The specimens represented in figures 3, 3a-c are all from Locality 68, Lower Ordovician Pogonip limestone, north- east of Adams Hill, Eureka district, Nevada. Fieure 3d. Ventral valve. U.S. Nat. Mus. Cat. No. 51541a. 3e. Partly exfoliated dorsal valve showing interior layers of the shell. U.S. Nat. Mus. Cat. No. 51541b. 3f. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 51541c. The specimens represented in figures 3d-f are from Locality 61, Upper Cambrian Dunderberg shale, south of the Hamburg mine, Eureka district, Nevada. Oxpotws sp. undt. a Walcott (p. 422). Figure 4. Ventral valve compressed in shaly limestone of Locality 338v, Lower Ordovician, 1 mile southwest of Middle Granville, Washington County, New York. U.S. Nat. Mus. Cat. No. 51652a Ibe ah PLATE XI. a. Area. h. Central muscle scar. ce. Trapezoidal area, including central, middle j- Anterior lateral muscle scar. lateral, and outside lateral muscle scars. OBOLUS TETONENSIS NINUS Walcott (p. 418). (Pl. VIII, figs. 11-0.] Ficures 1 and 1’. Top and side views of exterior of ventral valve, the type specimen. U. S. Nat. Mus. Cat. No. 51648a. la. Partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 51643b. 1b. Interior of ventral valve, showing outline of visceral area. U.S. Nat. Mus. Cat. No. 51643c. le. Dorsal valve, showing lamellation of shell. U.S. Nat. Mus. Cat. No. 51643d. ld and 1d’. Exfoliated dorsal valve, showing striation of interior layers of shell. U.S. Nat. Mus. Cat. No. 51643e. Je and 1f. Exfoliated dorsal valves, showing character of interior layers of shell and variation in form from specimens represented by figures lcand1d. U.S. Nat. Mus. Cat. Nos. 51643f and 516438¢, respectively. lg. Cast of broken dorsal valve, showing anterior position of visceral area, and the central and anterior lateral sears. U.S. Nat. Mus. Cat. No. 51643h. The specimens represented are all from Locality 9r, Upper Cambrian limestone in the Reagan sandstone, Coman- che County, Oklahoma. Oxsotus (WxsToNtIA) THEMIS Walcott (p. 466). Ficure 2. Exterior of ventral valve, the type specimen, showing broken edges of lamelle of the shell. U.S. Nat. Mus. Cat. No. 51732a. 2a. Dorsal valve, showing the same shell characters as figure 2. U.S. Nat. Mus. Cat. No. 51732b. 2b. Broken ventral valve, showing cast of the visceral cavity and main vascular trunks. U.S. Nat. Mus. Cat. No. 51732c. 2c. Partly exfoliated dorsal valve, posterior margin broken away. U.S. Nat. Mus. Cat. No. 51732d. The specimens represented are all from Locality 17e, Middle Cambrian sandy limestone on Grand View trail, south side Grand Canyon of the Colorado, Arizona. OBOLUS ISMENE Walcott (p. 393). Ficure 3. Portion of ventral valve, the type specimen, showing cardinal slopes and the striation of one of the inner layers of shell. U.S. Nat. Mus. Cat. No. 51545a. 3a. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 51545b. 3b. Interior of a dorsal valve showing area. U.S. Nat. Mus. Cat. No. 51545c. The specimens represented are all from Locality 369, Upper Cambrian sandstone in the Elvins formation, Flat River, St. Francois County, Missouri. OxsoLtus NuNDINA Walcott (p. 406). Figure 4. Ventral valve, the type specimen, showing the characteristic strong concentric ridges. 4a. Partly exfoliated dorsal valve. The specimens represented are on the same piece of limestone from Locality 14b, Upper Cambrian, Cold Creek, Llano County, Texas. U.S. Nat. Mus. Cat. Nos. 51587a and 51587b, respectively. OBoLus acapicus Walcott (p. 380). Figure 5. Cast of the interior of a dorsal valve, the type specimen, from Locality 3h, Upper Cambrian shale, McNeil Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51540a. The posterior portion of the shell was restored from another specimen (Catalogue No. 51540b), the two being counterparts. OBOLUS PHERES Walcott (p. 408). Figures 6 and 6a. Views of partly exfoliated ventral valves, showing thickness of the lamellated shell. U.S. Nat. Mus. Cat. No. 51589a and 51589b, respectively. Figure 6 represents the type specimen. 6b. Imperfect dorsal valve. U.S. Nat. Mus. Cat. No. 51589c. The specimens represented are all from Locality 10v, Upper Cambrian shale near Baraboo, Wisconsin. 42 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XI FRAN CES WIESER DEL. gv gc HELIOTYPE CO. BOSTON PLATE XI. 43 OsoLus SHANSIENSIS Walcott (p. 415). Figure 7. Broad form of the ventral valve from Locality €32, Middle Cambrian river drift on the Nankiang, 1 mile south of Chonpinghien, Shensi, China. U.S. Nat. Mus. Cat. No. 52537a. 7a. Narrow form of the ventral valve, the type specimen, from Locality €37, Middle Cambrian Kichou limestone, 8 miles south of Tinghianghien, Shansi, China. U.S. Nat. Mus. Cat. No. 52538a. 7b. Broad form of the dorsal valve associated with the ventral valve represented by figure 7. U.S. Nat. Mus. Cat. No. 52537b. 7c. Narrow form of the dorsal valve associated with the ventral valve represented by figure 7a. U.S. Nat. Mus. Cat. No. 52538b. Oxsotus Mryimus Walcott (p. 404). Figure 8. A partly exfoliated ventral valve, the type specimen, showing the cast of the visceral area and the main vascular canals. 8a. Exterior of dorsal valve. The specimens represented are both from Locality €1, Middle Cambrian Kiulung limestone, 2 miles south of Yen- chuang, Sintai district, Shantung, China. U.S. Nat. Mus. Cat. Nos. 52534a and 52534b, respectively. OBoLus oBscuRUS Walcott (p. 406). Ficure 9. Interior of an imperfectly preserved dorsal valve, the type specimen. U.S. Nat. Mus. Cat. No. 52536a. 9a. Exterior of an exfoliated, partly restored dorsal valve. U.S. Nat. Mus. Cat. No. 52536b. The specimens represented in figures 9 and 9a are both from Locality C63, Middle Cambrian sandy shale at the base of the Kiulung group, 3.5 miles southwest of Yenchuang, Sintai district, Shantung, China. Fiaure 9b. Partly exfoliated and broken ventral valve, showing concentric and radiating lines on the inner layers of the shell. U.S. Nat. Mus. Cat. No. 52535a. 9c. Enlargement of the concentric strie of the exterior surface. U.S. Nat. Mus. Cat. No. 52535b. 9d. Exterior surface of a broken dorsal valve. U.S. Nat. Mus. Cat. No. 52535c. The specimens represented in figures 9b-d are from Locality €75, Middle Cambrian limestone near the base of the Kichou formation, 4.5 miles south of Wutaihien, Shansi, China., Jeibye Meh) 2SIUE, PE Axeu a. Trapezoidal area, including central, middle j. Anterior lateral muscle scar. lateral, and outside lateral muscle scars. p. Pedicle groove. h. Central muscle sear. vs. Main vascular sinus. i. Transmedian muscle scar. ivs. Lateral branches of the vascular system. OBOLUS FEISTMANTELI (Barrande) (p. 391). [Pl]. XII, figs. 9 and 9a.] Ficure 1. Interior of ventral valve. Copied from Barrande [1879b, Pl. CVI, fig. 1v: 7A]. la. Cast of exterior surface of ventral valve, showing traces of concentric striz and lines of growth. Copied from Barrande [1879b, Pl. CVI, fig. 1v: 114A]. lb. Cast of interior of ventral valve. Original in the collection of the Museum of Comparative Zoology, Cam- bridge, Massachusetts; cast in the United States National Museum (Cat. No. 57088a). le. Cast of interior of ventral valve, showing lateral vascular canals. Original in the Museum of Com- parative Zoology; cast in the United States National Museum (Cat. No. 57088b). 1d. Interior of the type specimen, a ventral valve. Copied from Barrande [1879b, Pl. CVI, fig. rv: 4A]. le. Cast of the interior of a dorsal valve, showing traces of lateral vascular canals. Original in the Museum of Comparative Zoology; cast in the United States National Museum (Cat. No. 57088c). (See fig. 9a.) li. Enlargement of a portion of a partly exfoliated shell, showing structure of shell. Copied from Barrande [1879b, Pl. CVI, fig. rv: 12f]. The specimens represented are all from Locality 303i, Lower Ordovician sandstone, Etage dl, Kruschna Hora, 3ohemia. Oxso.Lus? ANCILLUS (Barrande) (p. 381). % Fieure 2. Partly exfoliated ventral valve, the type specimen, from Locality 303g, Lower Ordovician, Etage dl, Rabenberg, Bohemia. Copied from Barrande [1879b, Pl. CXI, fig. vi: 3A]. OBOLUS COMPLEXUS Barrande (p. 387). (Pl. XII, figs. 8 and 8a.] Fictre 3. Cast of interior of ventral valve, the type specimen, from Locality 303i, Lower Ordovician, Etage d1, Kruschna Hora, Bohemia. Copied from Barrande [1879b, Pl. CLII, fig. m: 4A]. 3a. Interior of dorsal valve from Locality 303i, Lower Ordovician, Etage dl, Kruschna Hora, Bohemia. Copied from Barrande [1879b, Pl. CXIII, fig. v: A]. OBoLUs ? MIRANDUS (Barrande) (p. 405). Ficure 4. Ventral valve, the type specimen, from Locality 303k, Lower Ordovician, Etage dl, Hradischt, Bohemia. Copied from Barrande [1879b, Pl. CXI, fig. 1: 3A]. 4a. Dorsal? valve from Locality 303k, Lower Ordovician, Etage dl, Hradischt, Bohemia. Copied from Barrande [1879b, Pl. CXI, fig. 1: 1A]. OBoLus? ADVENUs Barrande (p. 380). Ficure 5. Cast of interior of ventral valve, the type specimen, from Locality 303d, Lower Ordovician, Etage dl, Swarow, Bohemia. Copied from Barrande [1879b, Pl. XCV, fig. rv: 2A]. ; 5a and 5b. Exterior and side view of dorsal? valve from Locality 303d, Lower Ordovician, Etage d1, Swarow, Bohemia. Copied from Barrande [1879b, Pl. XCV, figs. 1v: 1A and 2B, respectively]. OxsoLus? ROKITZANENSIS Barrande (p. 411). Ficure 6. Cast of the interior of a ventral valve, the type specimen, from Locality 303b, Lower Ordovician, Etage dl, in the environs of Rokitzan, Bohemia, showing strong radiating striae. Copied from Barrande [1879b, Pl. CXXVI, fig. 1: 5A). 46 U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. xil FRANCES WIESER DEL, HELIOTYPE CO. BOSTON PLATE XII. 47 Oxotus? (WEsTONIA ?) LAMELLOSUS (Barrande) (p. 463). Ficure 7. Enlargement of a dorsal valve, the type specimen. Copied from Barrande [1879b, Pl. OVI, fig. 1: 2A]. 7a. Surface and lamelle of shell greatly enlarged. Copied from Barrande [1879b, Pl. CVI, fig. 1: 3f]. 7b. Elongate dorsal valve. Copied from Barrande [1879b, Pl. OXI, fig. rx: 2A). . 7c. Distorted ventral ? valve. Copied from Barrande [1879b, Pl. CXI, fig. 1x: 1A]. 7d. Enlargement of the surface of the specimen represented in figure 7c. Copied from Barrande [1879b, Pl. CXI, fig. rx: 1f]. The specimens represented are all from Locality 303 1, Lower Ordovician, Etage dl, Libetschoy, Bohemia. : OBoLus COMPLEXUS Barrande (p. 387). [PI. XII, figs. 3 and 3a.] Ficures 8 and 8’. Cast of interior and side outline of a ventral ? valve from Locality 303i, Lower Ordovician, Etage dl, Kruschna Hora, Bohemia. Copied from Barrande [1879b, Pl. XCV, figs. m1: 1A and 1B, respec- tively]. 8a. Supposed cast of interior of dorsal valve from Locality 303h, Lower Ordovician, Etage dl, Milinsky Wrch, near Woleschna, Bohemia. Copied from Barrande [1879b, Pl. XCV, fig. m1: 2C]. OBOLUS FEISTMANTELI (Barrande) (p. 391). (Pl. XII, figs. 1, la-f.] 9. Cast of the inner surface of the frontal rim of the shell, greatly enlarged. Original in the Museum of Com- parative Zoology; cast in the United States National Museum (Cat. No. 57088d). 9a. Traces of the minute terminal vessels that cross the inner surface near the anterolateral margins of the shell; greatly enlarged from a portion of the surface of the specimen represented by figure le. Original in the Museum of Comparative Zoology; cast in the United States National Museum (Cat. No. 57088c). The specimens represented are both from Locality 303i, Lower Ordovician sandstone, Etage dl, Kruschna Hora, Bohemia. ae ne Irby, OIE 62667°—vo1 51, pr 2—12—_+4 PLATE XIII. Oxsoius (BROGGERIA) SALTERI (Holl) (p. 424). [Pl. XV, figs. 4, 4a-d.] Figure 1. Exterior of ventral valve from Locality 309i, Upper Cambrian near Sandby, Province of Malméhus, Sweden. U.S. Nat. Mus. Cat. No. 51673a. la. Ventral valve associated with the specimen represented by figure 1, showing a cast of part of the interior of the shell. U.S. Nat. Mus. Cat. No. 51673b. 1b. Cast of the interior of a dorsal valve associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 51673c. le. Cast of the interior of a ventral valve from Locality 3091, Upper Cambrian, Sweden (exact locality unknown), showing the area, more or less of the main vascular sinuses, and the visceral cavity. U.S. Nat. Mus. Cat. No. 51398a. 1d. Cast of the interior of a ventral valve from Locality 101, Upper Cambrian shales, east bank of Barachois River, 6 miles from Little Bras d’Or Lake, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51671a. ; le. Cast of the interior of a ventral valve from Locality 3q, Upper Cambrian shales, Barachois Glen, 4 miles south of Little Bras d’Or Lake, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52441a. 1f, Cast of the interior ofa dorsal valve from Locality 3091, Upper Cambrian, Sweden (exact locality unknown). U.S. Nat. Mus. Cat. No. 51398b. lg. Cast of exterior of a ventral valve from Locality 10i, Upper Cambrian shales, Barachois River, north of Boisdale road, Cape Breton, Nova Scotia, with a portion of the shell covering the area broken away. U.S. Nat. Mus. Cat. No. 52442a. Th, li, and 1j. Casts of dorsal valves from Locality 101, Upper Cambrian shales, east bank of Barachois River, 6 miles from Little Bras d’Or Lake, Cape Breton, Nova Scotia, varying in outline, owing to compres- sion in the shale. U.S. Nat. Mus. Cat. Nos. 51671b, 51671c, and 51671d, respectively. 1k. Cast of dorsal valve from Locality 3q, Upper Cambrian shales, Barachois Glen, 4 miles south of Little Bras d’Or Lake, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52441b. 11. Cast of dorsal valve from Locality 10i; Upper Cambrian shales, Barachois River, north of Boisdale road, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52442b. Im. Cast of the interior of a dorsal valve from Locality 3238f, Ceratopyge limestone at Vestfossen, 10 miles west-southwest of Christiania, Norway, reproduced from a photograph. The markings of the vas- cular system are beautifully preserved in the cast. Univ. Min. Inst. Christiania, Norway. Specimen iliustrated by Brégger [1882, Pl. X, fig. 10] as Obolus saltert. In. Interior of a ventral valve from Locality 323w, Upper Cambrian at Christiania, Norway, flattened in shale. it is one of the largest shells of this species known to the author. Univ. Min. Inst. Christiania, Norway. Oxsotus (Acritis?) RuGATUS Walcott (p. 441). Fieure 2. Exterior view of the type specimen from Locality 58, Middle Cambrian Secret Canyon shale, New York and Secret canyons, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 35229a. Oxpo.us (AcriTIs) ANTIQUISSIMUS (Hichwald) (p. 437). [P]. XV, figs. 2, 2a-d.] Figure 3. Surface of shell enlarged four and one-half times. Locality 396d, passage beds between the Upper Cambrian and the Ordovician, ‘‘glauconite limestone,’ at Domglint, in Reval, Esthonia, Russia. U.S. Nat. Mus. Cat. No. 51534a. 50 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XIII FRANCES WIESER DEL. HELIOTYPE CO BOSTON PLATE Xv. PLATE XIV. e. Trapezoidal area, including central, middle 1. Outside lateral muscle sear. lateral, and outside lateral muscle scars. vs. Main vascular sinus. h. Central muscle scar. s. Median septum. i. Transmedian muscle sear. x. Heart-shaped cavity. j. Anterior lateral muscle sear. Oxsotus (ScHMipriA) CELATUS (Volborth) (p. 444). Figure 1. Exterior of ventral valve. U.S. Nat. Mus. Cat. No. 35237a. la. Interior of ventral valve. U.S. Nat. Mus. Cat. No. 35237b. Specimen figured by Walcott [1898b, PI. XXVI, fig. 1] as Obolus (Lingulella) celatus. 1b. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 35237c. lc. Interior of dorsal valve. U.S. Nat. Mus. Cat. No. 35237d. Specimen figured by Walcott [1898b, Pl. XXVI, fig. 2] as Obolus (Lingulella) celatus. The specimens represented are all from Locality 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia. Oso us (SCHMIDTIA) ACUMINATUS Mickwitz (p. 442). Figure 2. Exterior of ventral valve. U.S. Nat. Mus. Cat. No. 5153la. 2a. Interior of ventral valve. U.S. Nat. Mus. Cat. No. 51531b. 2b. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 51531c. 2c. Interior of dorsal valve. U.S. Nat. Mus. Cat. No. 51531d. The specimens represented are all from Locality 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia. Oxo us (Scumiprr1a) opTusus Mickwitz (p. 448). Figure 3. Exterior of ventral valve. U.S. Nat. Mus. Cat. No. 51532a. 3a. Interior of ventral valve. U.S. Nat. Mus. Cat. No. 51532b. 3b. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 51532c. 3c. Interior of dorsal valve. U.S. Nat. Mus. Cat. No. 51532d. The specimens represented are all from Locality 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia. Oxotus (ScumiIptr1A) crassus Mickwitz (p. 446). Ficure 4. Exterior of ventral valve. U.S. Nat. Mus. Cat. No. 51530a. 4a. Interior of ventral valve. U.S. Nat. Mus. Cat. No. 51530b. 4b. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 51530c. 4c. Interior of dorsal valve. U.S. Nat. Mus. Cat. No. 51530d. 4d. Interior of an elongate form of a dorsal valve. U.S. Nat. Mus. Cat. No. 51530e. The specimens represented are all from Locality 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia. LINGULELLA (LEPTEMBOLON) LINGULEZFORMIS (Mickwitz) (p. 542). Ficure 5. A large dorsal valve from Locality 396a, passage beds between the Upper Cambrian and the Ordovician, “slauconite sandstone,’ at Leppiko, near Leetz, Esthonia, Russia. Copied from Mickwitz [1896, Pl. III, figs. 17a-b]. 5a. Small dorsal valve associated with specimen represented by figure 5b. U.S. Nat. Mus. Cat. No. 51537a. 5b. Small ventral valve from Locality 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia. The beak of this specimen was broken away and has been restored in outline on the figure. U.S. Nat. Mus. Cat. No. 51537b. MONOGRAPH LI PL. XIV U, S. GEOLOGICAL SURVEY FRANCES WIESER DEL, MELIOTYPE CO BOSTON ay o PLATE XIV. 53 OBoLuUsS APOLLINIS Eichwald (p. 381). [Text figs. 4, p. 299, and 15, p. 299; and PI. VII, figs. 1-8, 10-17.] Figure 6. Exterior of a ventral valve. The portion of the frontal margin anterior to the crack running through it has been restored. e 6a. Exterior of adorsal valve. The portion of the frontal margin anterior to the crack running through it has been restored. The specimens represented in figures 6 and 6a can not now be located. The National Museum records give the locality as 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia, and the catalogue number as 51525. Six other specimens with this catalogue number are figured on Plate VII of this monograph. OBOLUS APOLLINIS MAXIMUS Mickwitz (p. 384). (Pl. VII, fig. 9.} Figure 7. Exterior of the central and posterior portions of a dorsal valve that illustrates the character of the outer surface of the numerous layers of the shell. From Locality 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia. U.S. Nat. Mus. Cat. No. 51528b. 7a. Partly exfoliated broken ventral valve, showing the impression of the main vascular sinuses on one of the inner layers of the shell, also the laminated character and interior markings of the shell. From Locality 336j, Upper Cambrian Obolus sandstone at Staroja Ladoga, Government of Novgorod, Russia. U.S. Nat. Mus. Cat. No. 26924a. ae = sf 4: * Acie: P " a‘ ne ah . Me Se Ova ND) OO PLATE XV. h. Central muscle sear. j. Anterior lateral muscle scar. Opotus (MIcKWITZELLA) stLuRIcus (Eichwald) (p. 434). Figure 1. Exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 51538a. la. Exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 51538b. 1b. Exterior surface of shell. Copied from Mickwitz [1896, Pl. III, fig. 9]. Ic. Enlargement of surface of ventral valve. U.S. Nat. Mus. Cat. No. 51538c. The specimens represented are all from Locality 396a, passage beds between the Upper Cambrian and the Ordo- vician, ‘“‘glauconite sandstone,” at Leppiko, near Leetz, Esthonia, Russia. Oxgotus (AcriITISs) ANTIQUISSIMUS (Hichwald) (p. 437). (Pl. XII, fig. 3.] Figures 2, 2a, and 2b. Ventral, side, and dorsal views of specimen preserving the two valves nearly united. The outer surface of the shell is almost entirely exfoliated. U.S. Nat. Mus. Cat. No. 51534b. 2c. Photographic enlargement of the exterior surface of the shell. U.S. Nat. Mus. Cat. No. 51534e. 2d. Exterior of a partly exfoliated dorsal valve, with the side outline of the two valves united. Copied from Mickwitz [1896, Pl. III, figs. 20a—b.] The specimens represented are all from Locality 396d, passage beds between the Upper Cambrian and the Ordo- vician, ‘‘glauconite limestone,” at Domglint, in Reval, Esthonia, Russia. OBOLUS ELEGANS Mickwitz (p. 390). Fieure 3. Exterior of a ventral? valve showing a strongly marked surface. Specimen from Locality 395b, Upper Cambrian Obolus sandstone at Ilgast, Esthonia, Russia. U.S. Nat. Mus. Cat. No. 51535a. OxsoLus (BROGGERIA) SALTERI (Holl) (p. 424). [Pl. XIU, figs. 1, lan.] Figure 4. Figure of ventral valve, the type specimen, from Locality 304e, Upper Cambrian “‘Black shales” at Coal Hill, Malvern Hills, England. Copied from Holl [1865, p. 101, fig. 9]. The figure was also copied by Davidson [1866, Pl. IV, figs. 28a and 28]. 4a and 4b. Ventral and dorsal valves occurring in Locality 310h, Upper Cambrian dark argillaceous shale somewhere in Skane (Provinces of Malméhus and Christianstad), Sweden. U.S. Nat. Mus. Cat. Nos. 1493la and 14931b, respectively. 4c. Cast of dorsal valve from Locality 309j, Upper Cambrian argillaceous shale at Alunbruk, Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 51676a. 4d. Partly exfoliated dorsal valve from Locality 309h, Upper Cambrian very dark siliceous limestone at Fogelsang, Province of Malméhus, Sweden. U. 8. Nat. Mus. Cat. No. 51674a. : Oxso.tus? pALLiaTuS Barrande (p. 407). Figure 5. Exterior surface of dorsal valve, the type specimen, from Locality 308c, passage beds between the Cam- brian and Ordovician, in the suburbs of Hof, Bavaria, Germany, one-third natural size. Copied from Barrande [1868a, fig. 65]. Oxso.tus? minor Barrande (p. 405). Ficure 6. Exterior surface of ventral valve, the type specimen, from Locality 308¢, passage beds between the Cam- brian and Ordovician, in the suburbs of Hof, Bavaria, Germany, one-third natural size. Copied from Barrande [1868a, fig. 68]. ACROTRETA INCHOANS (Barrande) (p. 690). Ficures 7 and 7a. Two views copied from Barrande [1868a, figs. 74 and 75] of shells from Locality 303c, passage beds between the Cambrian and the Ordovician, suburbs of Hof, Bavaria, Germany. Figure 7 is the type. 56 U. S. GEOLOGICAL SURVEY MONOGRAPH Li PL. XV gD a . = EF = ed ‘ el wt \ eS iN ye We S te FRANCES WIESER DEL. HELIOTYPE CO. BOSTON PLATE XV. 57 OBoLus? sp. undt. e Kayser (p. 423). Figure 8. Ventral valve associated with Hoorthis saltensis in Locality 389b, Upper Cambrian sandstone at Tilcuya, Province of Jujuy, Argentina. Copied from Kayser [1876, Pl. I, fig. 14]. Oso us? sp. undt. f Kayser (p. 423). Figure 9. Several valves on small fragment of limestone from Locality 332, Upper Cambrian at Saimaki, Liaotung, China. Copied from Kayser [1883, Pl. III, fig. 2]. Oxo us? BAvARICUS (Barrande) (p. 385). Ficure 10. Ventral valve, the type specimen, from Locality 303c, passage beds between the Cambrian and Ordo- vician, suburbs of Hof, Bavaria, Germany. Copied from Barrande [1868a, fig. 62], who described it as Lingula bavarica. 10a. Dorsal valve associated with the shell represented by figure 10 in Locality 303ce. Copied from Barrande [1868a, fig. 64], who described it as Obolus? palliatus. Oxso.us scumiptr Mickwitz (p. 412). Figures lla-c. Exterior, side, and interior views of a dorsal valve, the type specimen, from Locality 395, Upper Cambrian Obolus sandstone at Joa, near Jegelecht, Esthonia, Russia. Copied from Mickwitz [1896, Pl. II, figs. 14a-c]. OxsoLus? MurRAyYI Billings (p. 405). Figure 12. Figure of the original type specimen from Locality 314g, Lower Ordovician, Maiden Arm, Hare Bay, northern Newfoundland. Geol. Survey Canada. The specimen is the one on which Billings [1865, p. 362] based his species, but he did not figure it. : Ei AGE eval PLATE XVI. a. Central lateral space of area. k. Middle lateral muscle scar. a’. Outer lateral space of area. 1. Outside lateral muscle scar. ce. Trapezoidal area, including central, middle p. Pedicle groove. lateral, and outside lateral muscle scars. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. i. Transmedian muscle scar. x. Heart-shaped cavity. j. Anterior lateral muscle scar. Oxsotus (LINGULOBOLUS) AFFINIS (Billings) (p. 431). Figure 1. Cast of the interior of a ventral valve showing the characteristic viséeral cavity. U.S. Nat. Mus. Cat. No. 51679a. la. Cast of a portion of the interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51679b. lb. Cast of the interior of a ventral valve showing the ae - the deep impressions in which the muscle scars are situated. U.S. Nat. Mus. Cat. No. 51679c. le. Cast of the interior of a dorsal valve showing the position of the central and anterior lateral muscle scars. U.S. Nat. Mus. Cat. No. 51679d.- ld. Partly exfoliated dorsal valve showing the area and the varied surface of the inner layers of the shell. U.S. Nat. Mus. Cat. No. 51679e. ie. Outline of the area of a dorsal valve. U.S. Nat. Mus. Cat. No. 51679f. The specimens represented are all from Locality 114b, Lower Ordovician sandstone, 1 mile north of Lance Cove, Great Belle Island, Conception Bay, Newfoundland. Oxso.tus (LinGULOBOLUS) sPIssus (Billings) (p. 432). [Pl. XLH, figs. 3, 3a.] Figure 2. Dorsal valve from which the outer layers of the shell have been exfoliated so as to show the outline of the visceral cavity and vascular sinuses. U.S. Nat. Mus. Cat. No. 51678 1. Part of the inner surface of this specimen is enlarged on Plate XLII, figure 3a. 29. Cast of the interior of a dorsal valve, on which portions of the shell remain over ‘the muscle scars. U.S. Nat. Mus. Cat. No. 51678a. 2b. Dorsal valve preserving a portion of the outer surface of the shell, which is enlarged in Plate XLII, figure 3. U.S. Nat. Mus. Cat. No. 51678b. 2e. Partly exfoliated dorsal valve showing something of the character and arrangement of the inner layers of the shell. U.S. Nat. Mus. Cat. No. 51678c. 2d. Partly exfoliated dorsal valve illustrating how the impressions of the vascular sinuses and markings are preserved on the various layers of the shell. U.S. Nat. Mus. Cat. No. 51678d. 2e. Inner layers of the central portion of a ventral valve, showing the characteristic trapezoidal area and vascular sinuses of Obolus. U.S. Nat. Mus. Cat. No. 51678e. 2f. Partly exfoliated dorsal valve illustrating peculiarities of the shell not shown by other figures. U.S. Nat. Mus. Cat. No. 51678f. Qe. Cast of the interior of a dorsal valve with vertical and transverse outline of the convexity of the shell. U.S. Nat. Mus. Cat. No. 51678g. 2h. Partly exfoliated dorsal valve that is more elongate than most specimens. U.S. Nat. Mus. Cat. No. 51678h. 2i. An unusually well preserved ventral valve, showing the various layers forming the shell. U. S. Nat. Mus. Cat. No. 51678i. 2j. Interior of a ventral valve as shown by the impression made on the laminated inner layers of the shell, the outer layers being exfoliated. U.S. Nat. Mus. Cat. No. 51678}. 2k. Cast of the interior of a ventral valve, showing muscle scars and vascular markings essentially the same as those of Obolus. U.S. Nat. Mus. Cat. No. 51678k. The specimens represented are all from Locality 114b, Lower Ordovician sandstone, 1 mile north of Lance Cove, Great Belle Island, Conception Bay, Newfoundland. 60 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XVI Wt ba Hi Lit He FRANCES WIESER DEL. HELIOTYPE CO BOSTON PLATE . Central lateral space of area. - Outer lateral space of area. XVII. m. Pedicle muscle sear. p. Pedicle groove. , © Trapezoidal area, including central, ps. Parietal band. middle lateral, and outside lateral s. Median septum. muscle scars. v. Visceral cayity. f. Flexure line of area. vs. Main vascular sinus. g. Umbonal muscle scar. ivs. Lateral branches of vascular system. h. Central muscle scar. pvs. Peripheral branches of the vascular . Transmedian muscle scar. . Anterior lateral muscle scar. . Middle lateral muscle scar. system. x. Heart-shaped cavity. z. Same as ivs of the ventral valve. Ped PUL esol bas . Outside lateral and middle lateral muscle scars. LINGULELLA ACUTANGULA (Roemer) (p. 474). Figure 1. Ventral valve in limestone, from which the shell is partly exfoliated. Locality 69, Upper Cambrian, Honey Creek, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 27412a. The area of this shell is enlarged in figure 1d. la. Cast of the interior of a ventral valve from Locality 353¢, Upper Cambrian sandstone, Llano County, Texas, showing concentric lines of tubercles that fill the puncte of the interior surface of the shell. U.S. Nat. Mus. Cat. No. 35240a. The area of this shell is enlarged in figure 1b. 1b. Enlargement of cast of area and pedicle groove of figure la. U.S. Nat. Mus. Cat. No. 35240a. le. Cast of interior of ventral valve, from same locality as the specimen represented in figures la and 1b, in which the cast of the visceral cavity and muscle scars is unusually prominent. U.S. Nat. Mus. Cat. No. 35240b. Copied from Walcott [1898b, Pl. XX VII, fig. 6]. 1d. Enlargement of the cast of the area of the specimen represented by figure 1. 274124. le. Ventral valve in sandstone from Locality 68, Upper Cambrian, Packsaddle Mountain, Llano County, Texas. U.S. Nat. Mus. Cat. No. 27410a. : 1f. Cast of the interior of a ventral valve showing the muscle scars unusually well preserved. Upper Cambrian sandstone, Llano County, Texas. U.S. Nat. Mus. Cat. No. 35240c. Walcott [1898b, Pl. XXVIII, fig. 1]. lg. Cast of the interior of a ventral valve from Locality 69, Upper Cambrian limestone, Honey Creek, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 27412b. lh. Cast of the interior of a dorsal valve from Locality 3&3¢e, Upper Cambrian sandstone, Llano County, Texas, in which the interior lateral branches (z) of the vascular system are shown. U.S. Nat. Mus. Cat. No. 35240d. Copied from Walcott [1898b, Pl. XX VIII, fig. 2]. li. Cast of the interior of a dorsal valve from Locality 69, Upper Cambrian limestone, Honey Creek, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 27412c. lj. Cast of the interior of a dorsal valve which shows that the punctate surface of the interior of the shell did not extend to the outer border. From Locality 353e, Upper Cambrian sandstone, Llano County, Texas. U.S. Nat. Mus. Cat. No. 35240e. 1k. Cast of the interior of a dorsal valve from Locality 68e, Upper Cambrian sandy limestone, Packsaddle Mountain, Llano County, Texas. U.S. Nat. Mus. Cat. No. 27410b. 1]. Enlargement of a portion of a ventral valve showing the outer surface in front of the line a/” a” and the surface of one of the inner layers of the shell back of a’ a’’. U.S. Nat. Mus. The specimen from which this figure was drawn can not be located; even the locality is unknown. Im. Median, longitudinal, thin section through the central portion of a ventral valve; os=thin outer layer without traces of structure; is=obliquely laminated inner layer; il=interior lamella produced by the thickening of the shell. U.S.-Nat. Mus. Cat. No. 27410c. In. Central portion of a transverse median thin section; os=thin outer layer; is=obliquely laminated inner layer. U.S. Nat. Mus. Cat. No. 27410d. lo. Median longitudinal section through the posterior portion of a ventral valve. Lettering same as for figure Im. U.S. Nat. Mus. Cat. No. 27410e. U.S. Nat. Mus. Cat. No. Locality 358¢e, Copied from The specimens thin-sectioned for reproduction in figures 1m, In, and lo came from Locality 68e, Upper Cambrian sandy limestone, Packsaddle Mountain, Llano County, Texas. 62 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XVII ivs 1" FRANCES WIESER DEL. HELIOTYPE CO BOSTON is) Sere PLATE XVIII. a. Central lateral space of area. j. Anterior lateral muscle scar. a’. Outer lateral space of area. p. Pedicle groove. f. Flexure line of area. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. LINGULELLA MostA (Hall) (p. 520). Ficure 1. Cast showing part of the interior of a ventral valve from Locality 85s, Upper Cambrian sandstone at Prairie du Sac, Wisconsin. U.S. Nat. Mus. Cat. No. 27370a. la. Cast of a compressed ventral valve from Locality 85x, Upper Cambrian sandstone near Mazomanie, Wisconsin.. U.S. Nat. Mus. Cat. No. 27373a. 1b. Cast of a ventral valve from Locality 78s, Upper Cambrian sandstone in suburbs of Osceola, Wisconsin. U.S. Nat. Mus. Cat. No. 27371a. a 1c. Cast of the interior of a compressed specimen of a ventral valve, showing traces of the interior markings. Locality S85x, Upper Cambrian sandstone near Mazomanie, Wisconsin. U.S. Nat. Mus. Cat. No. 27373b. 1d. Cast of the interior of a dorsal valve from Locality 78s, Upper Cambrian sandstone near Osceola, Wis- _consin. U.S. Nat. Mus. Cat. No. 27371b. le. Cast of a more elongate dorsal valve from Locality 78, Upper Cambrian sandstone near Osceola, Wis- consin. U.S. Nat. Mus. Cat. No. 27371c. 1f. Cast of a dorsal valve that is much broader posteriorly than most dorsal valves of the species. Locality 86, Upper Cambrian sandstone at Gibraltar Bluff, Lodi, Wisconsin. U.S. Nat. Mus. Cat. No. 27372a. A specimen from Locality S85x (Cat. No. 27373c) was used to restore portions of this figure. LINGULELLA MOSIA OSCEOLA (Walcott) (p. 521). Ficure 2. Cast of a ventral valve, the type specimen, from Locality 78, Upper Cambrian sandstone near Osceola, Wisconsin. U.S. Nat. Mus. Cat. No. 27327a. 2a. Cast of ventral valve from Locality 78s, Upper Cambrian sandstone near Osceola, Wisconsin. U.S. Nat. Mus. Cat. No. 27327b. 2b. Enlargement of the area of the cast of a ventral valve, associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 27327¢ 2c. Cast of a dorsal valve associated with the ventral valve represented by figure2 U.S. Nat. Mus. Cat. No. 27327d. LINGULELLA Winona (Hall) (p. 539). Fictre 3. Cast of ventral valve from Locality 78¢, Upper Cambrian sandstone at Osceola, Wisconsin. U.S. Nat. Mus. Cat. No. 27400a. 3a. Partly exfoliated ventral valve from Locality 85s, Upper Cambrian sandstone at Prairie du Sac, Wis- consin. U.S. Nat. Mus. Cat. No. 33856a. 3b. Partly exfoliated dorsal valve, associated with the specimen represented by figure 3a. U.S. Nat. Mus. Cat. No. 33856b. LINGULELLA WINONA CONVEXA (Walcott) (p. 540). Figure 4, Two ventral valves, natural size, from Locality S85x, Upper Cambrian sandstone near Mazomanie, Wisconsin. U.S. Nat. Mus. Cat. No. 51854a. 4a, and 4b. Casts of ventral valves showing area. Locality 78, Upper Cambrian sandstone near Osceola, Wisconsin. U.S. Nat. Mus. Cat. Nos. 35235a and 35235b, respectively. Figure 4a represents the type specimen. 4c, Cast of the usual form of dorsal valve. Same locality as specimen represented by figure 4a. U.S. Nat. Mus. Cat. No. 35235c. : 4d. Cast of an elongate form of dorsal valve, showing central and anterior lateral scars. Same locality as speci- men represented by figure 4a. U.S. Nat. Mus. Cat. No. 35235d. 64 PL. XV MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL, (0. BOSTON HELIOTVPE PLATE XVIII. 65 LINGULELLA OWENI (Walcott) (p. 523). Ficure 5. Ventral valve showing the exterior surface of the shell, from Locality 86, Upper Cambrian sandstone at Gibraltar Bluff, Lodi, Wisconsin. U.S. Nat. Mus. Cat. No. 25330a. 5a. Enlargement of the area of a cast of a flattened ventral valve in which all traces of a flexure line have been lost. Locality 85s, Upper Cambrian sandstone at Prairie du Sac, Wisconsin. U.S. Nat. Mus. Cat. No. 27385a. - 5b. Cast of the interior of a dorsal valve, the type specimen, associated with the specimen represented by figure 5. U.S. Nat. Mus. Cat. No. 25330b. 5c. A smaller and less elongate dorsal valve than that represented by figure 5b, but from the same locality. U.S. Nat. Mus. Cat. No. 25330c. 5d and 5e. Casts of small ventral valves from Locality 78c, Upper Cambrian, sandstone at Osceola, Wis- consin. U.S. Nat. Mus. Cat. Nos. 27329a and 27329b, respectively. 5f. Cast of a dorsal valve from same locality as specimens represented by figures 5d and 5e. U.S. Nat. Mus. Cat. No. 27329c. OxBoLus piscoipEUs (Hall and Whitfield) (p. 389). Figure 6. Exterior ofa partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 24555a. 6a. Dorsal valve, partly exfoliated. U.S. Nat. Mus. Cat. No. 24555b. 6b and 6c. Probably ventral valves, but it is difficult to determine owing to the rounding of the posterior portion of the valve. U.S. Nat. Mus. Cat. Nos. 24555e and 24555d, respectively. Figure 6c is drawn from the type specimen figured by Hall and Whitfield [1877, Pl. I, fig. 2]. The specimen repre- sented by their figure 1 is not redrawn in this monograph. The specimens represented by figures 6, 6a-c are all from Locality 313j, Upper Cambrian limestone in the Eureka district, Nevada. Figure 6d. Partly exfoliated dorsal valve, showing outline of visceral area, from Locality 62, Upper Cambrian Dunderberg shale, north of Adams Hill, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 51547a. 62667°—vot 51, pr 2—12 5 : ane a hy os | PLATE XIX Figure FIGURE PLATE XIX. h. Central muscle scar. v. Visceral cavity. j. Anterior lateral muscle scar. vs. Main vascular sinus. s- Median septum. LINGULELLA BELLULA (Walcott) (p. 482). 1. Cast of a ventral valve from Locality 114, Upper Cambrian upper sandstone beds of Little Belle Island, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 27309a. la. Cast of the interior of a small ventral valve, the type specimen, from Locality 114a, Upper Cambrian arenaceous shales about 50 feet below the sandstone of Locality 114, Little Belle Island, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 57082a. 1b. Cast of the interior of a ventral valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 57082b. le. Cast of the interior of a dorsal valve, showing the arching of the parietal band outward to the main vascular sinus, associated in the shale with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 57082c. id. Cast of the interior of a dorsal valve, showing the median septum and what may be the central muscle scars, associated in the shale with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 57082d. le. Interior of a dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 57082e. LINGULELLA BELLA: (Walcott) (p. 481). [Pl. XXXVI, fig. 4.] 2. Cast of the interior of a ventral valve from Locality 114a, Upper Cambrian arenaceous shale beneath the upper sandy beds on Little Belle Island, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 27307a. 2a. Cast of the interior of a ventral valve, associated with specimen represented by figure 2, but which is more strongly marked by concentric and radiating strie. U.S. Nat. Mus. Cat. No. 27307b. 2b. Cast of the interior of a dorsal valve, the area of which, owing to fracture, slightly resembles the area of a ventral valve. From the same bed and locality as specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 27307c. 2c. A somewhat broader dorsal valve than that represented by figure 2b, but associated in the same bed with it. U.S. Nat. Mus. Cat. No. 27307d. 2d. Cast of the interior of a ventral valve from Locality 114b, Lower Ordovician sandstone 1 mile north of Lance Cove, Great Belle Island, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 27308a. 2e. Finely preserved dorsal valve, associated in the same bed with specimen represented by figure 2d. U.S. Nat. Mus. Cat. No. 27308b. 2f. Cast of the interior of a convex ventral valve from Locality 114, Upper Cambrian upper sandstone beds of Little Belle Island, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 57081a. 2¢. Enlargement of a cast of the area of a dorsal valve, associated in the bed with specimens represented by figures 2d and 2e. U.S. Nat. Mus. Cat. No. 27308c. 2h. Finely preserved ventral and dorsal valves from which the thin outer surface has been exfoliated, the type specimen, associated in the same bed with specimen represented by figure 2d. U.S. Nat. Mus. Cat. No. 27308d. 2i. Dorsal valve from Locality 114b, see figure 2d. U.S. Nat. Mus. Cat. No. 27308e. 2j. Cast of the interior of a ventral valve, natural size, from Locality 114b, see figure 2d. U.S. Nat. Mus. Cat. No. 27308f. : 2k and 21. Exterior of ventral valves from Locality 114b, see figure 2d. U.S. Nat. Mus. Cat. Nos. 27308g and 27308h, respectively. 2m. Dorsal valve. U.S. Nat. Mus. Cat. No. 273081. 2n. Dorsal valve. U.S. Nat. Mus. Cat. No. 27308). 20. Dorsal valve. U.S. Nat. Mus. Cat. No. 27308k. 2p. Dorsal valve. U.S. Nat. Mus. Cat. No. 27308 1. 2q. Dorsal valve. U.S. Nat. Mus. Cat. No. 27308m. DNRM Figures 2i, 2m-q illustrate variations in the size and outline of dorsal valves from Locality 114b, Lower Ordovician sandstone, 1 mile north of Lance Cove, Great Belle Island, Conception Bay, Newfoundland. 68 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL, XIX FRANCES WIESER DEL. HELIOTYFE co by One ~ : Tinie ay PILATE) XX. 69 LINGULELLA ELLSI (Walcott) (p. 495). Fiaure 3. Ventral valve, the type specimen, slightly distorted by compression, showing the area. U.S. Nat. Mus. Cat. No. 27315a. 3a. Cast of a ventral valve, showing the area and outlines of the visceral cavity. U.S. Nat. Mus. Cat. No. 27315b. 3b. Dorsal valve crushed down into the ventral valve. U.S. Nat. Mus. Cat. No. 27315c. 3c. Dorsal valve slightly distorted by compression. U.S. Nat. Mus. Cat. No. 27315d. The specimens represented are all from Locality 220a, Ordovician siliceous shales at the Grand Trunk railroad bridge over Chaudiere River, Quebec, Canada. LINGULELLA La&vis Matthew (p. 512). Figure 4. A large dorsal valve, the type specimen. University of Toronto, Canada. Specimen figured by Matthew (1892, Pl. XII, fig. 4b]. 4a. Ventral valve flattened in shale. University of Toronto, Canada. Specimen figured by Matthew [1892, Pl. XII, fig. 4a). 4b. Ventral valve flattened in the shale. University of Toronto, Canada. The specimens represented are all from Locality 301n, Upper Cambrian shales near the falls at St. John, New Brunswick. LINGULELLA LEVIS GRANDIS Matthew (p. 512). Figure 4c. Cast of the interior of a dorsal valve from Locality 325b, Upper Cambrian shale at Escasonie Shore, East Bay, Cape Breton, Nova Scotia. University of Toronto, Canada. Specimen figured by Matthew [1903, Pl. XV, fig. 1d]. LInGULELLA (LINGULEPIS) spaTULA (Walcott) (p. 558). Figure 5. Nearly perfect ventral valve, the type specimen, from which the outer surface has been exfoliated. U.S. Nat. Mus. Cat. No. 35290a. ; 5a. Dorsal valve preserving concentric and radiating striae beneath the outer surface. U.S. Nat. Mus. Cat. No. 35290b. 5b. Cast of the dorsal valve, showing cast of median ridge and pits on the inner surface. U.S. Nat. Mus. Cat. No. 35290c. The specimens represented are all from Locality 74d, Middle Cambrian sandstones in Bass Canyon, Grand Canyon of the Colorado, Arizona. Ua ate me nA ‘ P i mf Qnty Ar Wis in f ons PLATE XX. h. Central muscle scar. y. Visceral cavity. j. Anterior lateral muscle sear. vs. Main vascular sinus. s. Median septum. x. Heart-shaped cavity. LINGULELLA MANTICULA (White) (p. 517). Figure 1. Cast of the interior of a ventral valve from Locality 313f, Upper Cambrian limestone at Schellbourne, Schell Creek Range, Nevada. U.S. Nat. Mus. Cat. No. 8569a. la. Dorsal valve associated on the same hand specimen with the valve represented by figure 1. U.S. Nat. Mus. Cat. No. 8569b. lb. Cast showing part of the interior of a more elongate dorsal valve than that represented by figure la, but associated on the same hand specimen with it. U.S. Nat. Mus. Cat. No. 8569c. 1c. Type specimen, the ventral valve, from the locality represented by figures 1, la-b. U.S. Nat. Mus. Cat. No. 8569d. When the plates were made up this specimen could not be located and the original drawing prepared for White [1877, Pl. III, fig. 2b] was used. The specimen has been found on the same hand specimen with the type of Acrotreta pyxidicula. OpoLus RoTUNDATUS (Walcott) (p. 411). Figure 2. A ventral valve, the type specimen, from Locality 318d, Lower Ordovician limestone near Schellbourne, Schell Creek Range, Nevada. U.S. Nat. Mus. Cat. No. 27337a. 2a. Cast of the interior of a dorsal valve associated with the shell represented by figure 2. U.S. Nat. Mus. Cat. No. 27337b. 2b. Ventral valve from Locality 160a, Upper Cambrian limestone, west of Bear Creek, south of Gallatin Valley, Montana. U.S. Nat. Mus. Cat. No. 27338a. 2c. A small but very perfect ventral valve associated with the valve represented by figure 2b. U.S. Nat. Mus. Cat. No. 27338b. 2d. A small and characteristic dorsal valve associated with the valves represented by figures 2b and 2c. U.S. Nat. Mus. Cat. No. 27338c. 2e. Dorsal valve from Locality 302b, Middle Cambrian limestones near Crowfoot Ridge, Yellowstone National Park, Wyoming. U.S. Nat. Mus. Cat. No. 35207a. Specimen figured by Walcott [1899, Pl. LX, fig. 2a] as the dorsal valve of Obolus (Lingulella) desideratus. (See description of fig. 4, below.) / LINGULELLA POGONIPENSIS (Walcott) (p. 525). Ficure 3. Ventral valve, the type specimen, showing cast of the area and the pedicle furrow. U.S. Nat. Mus. Cat. No. 27332a. ; 3a. Small, partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 27332b. 3b. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 27332c. 3c. Partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 27332d. The specimens represented are all from Locality 201, passage beds between the Upper Cambrian and the Ordovician, in the ridge east of Hamburg Ridge, Eureka district, Nevada. LINGULELLA DESIDERATA (Walcott) (p. 492). Ficure 4. Partly exfoliated ventral valve from Locality 302 1, Upper Cambrian limestone, Gallatin Range, Yellow- stone National Park, Wyoming. U.S. Nat. Mus. Cat. No. 33867a. Type specimen, figured by Walcott [1899, Pl. LX, fig. 2] as Obolus (Lingulella) desideratus.. (See description of fig. 2e, above.) 4a. Dorsal valve, associated with the specimen represented by figure 4. U.S. Nat. Mus. Cat. No. 33867b. 4b and 4c. Ventral and dorsal valves on the same piece of limestone from Locality 61, Upper Cambrian, near the Hamburg mine, Eureka district, Nevada. U. S. Nat. Mus. Cat. Nos. 27313a and 27313b, respectively. 5 and 5a. Ventral valves from Locality 94xx, Middle Cambrian shaly limestones at Givens Mill, on Cowan Creek, Cherokee County, Alabama. U.S. Nat. Mus. Cat. Nos. 27355a and 27355b, respectively. 5b. Ventral valve from Locality 930, Upper Cambrian shales near Jordans, on Cowan Creek, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 56990a. 5c. Dorsal valve, slightly distorted in outline, from Locality 940, Upper Cambrian shale near Givens Ford, on Cowan Creek, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 56991a. 72 xX REE MONOGRAPH LI U, S. GEOLOGICAL SURVEY VIESER DEL. FRANCES \ Vik the CP ite pede PAE) XOXe 73 LINGULELLA DESIDERATA (Walcott)—Continued. Figure 5d. Ventral valve from Locality 96, Upper Cambrian limestone near Rome, Floyd County, Georgia, marked by unusually strong concentric striae. U.S. Nat. Mus. Cat. No. 51823a. 5e. Dorsal valve associated with the ventral valve illustrated by figure 5d. U.S. Nat. Mus. Cat. No. 51823b. df and 5g. Dorsal valves from Locality 10%7a, Upper Cambrian shaly limestone near Copper Ridge, 11 miles northwest of Knoxville, Tennessee. U.S. Nat. Mus. Cat. Nos. 27312a and 27312b, respectively. 5h. Large ventral valve from Locality 93, Upper Cambrian shales near Jordans on Cowan Oreek, Cherokee County, Alabama, referred to this species with some doubt. U.S. Nat. Mus. Cat. No. 56990b. 5i. Broad dorsal valve from Locality 93a, Upper Cambrian shales on the Terrapin Creek road from Center to Amberson, Cherokee County, Alabama, that is doubtfully referred to this species, although there is considerable difference in the form of the shell in most localities at which it occurs. U.S. Nat. Mus. Cat. No. 51841a. 5j. Form similar to that in figure 5i, from Locality 302b, Upper Cambrian limestone near Crowfoot Ridge, Yellowstone National Park, Wyoming. U.S. Nat. Mus. Cat. No. 2731la. Specimen figured by Walcott [1899, Pl. LX, fig. 3] as Dicellomus nanus. LInGULELLA PuNCTATA (Walcott) (p. 528). Ficure 6. Partly exfoliated ventral valve from Locality 58, Middle Cambrian Secret Canyon shale, Secret and New York canyons, Eureka district, Nevada, showing cast of part of the interior surface of the shell. U.S. Nat. Mus. Cat. No. 27335a. Type specimen, figured by Walcott [1884b, Pl. 1X, fig. 3] as Lingula? manticula. 6a. Partly exfoliated dorsal valve associated in the same piece of limestone with the specimen represented by figure 6. U.S. Nat. Mus. Cat. No. 27335b. Specimen figured by Walcott [1884b, Pl. XI, fig. 2] as Lingula ? manticula. PLATE XXI. f. Flexure line of area. p. Pedicle groove. g. Umbona] muscle sear. s. Median septum. h. Central muscle scar. v. Visceral cavity. j. Anterior lateral muscle sear. : vs. Main vascular sinus. LINGULELLA PERATTENUATA (Whitfield) (p. 523). Figure 1. Cast of the interior of a ventral valve from Locality 355, Middle Cambrian sandstones on Red Canyon Creek, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 27423a. la. Cast of the interior of a ventral valve from Locality 74, Middle Cambrian sandstone, head of Nunkoweap Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 51796a. 1b. Narrow, partly exfoliated ventral valve, with the apex rounded, from Locality 355, Middle Cambrian sandstones on Red Canyon Creek, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 24589a. Type specimen, figured by Whitfield [1880, Pl. II, fig. 9] as Lingulepis perattenuatus. Je. Cast of the interior of a ventral valve associated with the valve represented by figure 1. U.S. Nat. Mus. Cat. No. 27423b. This specimen occurs on the same hand specimen with figured specimens of Lin- gulella (Lingulepis) acwminata. 1d. Cast of the interior of a dorsal valve associated with the valves represented by figureslandlc. U.S. Nat. Mus. Cat. No. 27423c. le. Cast. of the interior of a ventral valve from Locality 67¢, Upper Cambrian sandstone, Tatur Hill, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 27424a. lf. Partly exfoliated dorsal valve from Locality 68y, Upper Cambrian sandstone, Packsaddle Mountain, Llano County, Texas. U.S. Nat. Mus. Cat. No. 27422a. lg. Partly exfoliated dorsal valve associated with the valve represented by figure 1f. U.S. Nat. Mus. Cat. No. 27422b. lh. Cast of the interior of a dorsal valve associated on the same hand specimen with the valve represented by figure Ib. U.S. Nat. Mus. Cat. No. 24589b. Specimen figured by Whitfield [1880, Pl. II, fig. 8] as Lingulepis perattenuatus. li. Cast of the interior of a dorsal valve associated with the valves represented by figures 1b and 1h. U.S. Nat. Mus. Cat. No. 24589c. Specimen figured by Whitfield [1880, PI. II, fig. 7] as Lingulepis perattenuatus. LINGULELLA simILtis (Walcott) (p. 532). Ficure 2. Cast of the interior of a ventral valve, the type specimen, from Locality 88a, Middle Cambrian limestone, near Deadwood, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 27339a. 2a. Cast of the interior of a dorsal valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 27339b. 2b and 2c. Partly exfoliated ventral and dorsal valves, respectively, associated with the specimens repre- sented by figures 2 and 2a. U.S. Nat. Mus. Cat. Nos. 27339c¢ and 27339d, respectively. 2d. Small, strongly convex dorsal? valve doubtfully referred to this species, from same locality and bed of limestone as the specimens represented by figures 2, 2a-c. U.S. Nat. Mus. Cat. No. 27339e., 2e. Cast of the interior of an unusually convex, elongate ventral valve. U.S. Nat. Mus. Cat. No. 27340a. 2f. Cast of the interior of a ventral valve that narrows toward the frontal margin. U.S. Nat. Mus. Cat. No. 27340b. 2g and 2h. Casts of two dorsal valves that show variation in outline. U.S. Nat. Mus. Cat. Nos. 27340c and 27340d, respectively. 2i and 2]. Casts of associated ventral and dorsal valves that approach most closely the typical forms from the Black Hills. U.S. Nat. Mus. Cat. Nos. 27340e and 27340f, respectively. The specimens from which figures 2e to 2j are drawn are all from Locality 97a, Upper Cambrian sandstone, at Win- field, Wisconsin. Fieures 3 and 3a. Casts of the interior of ventral valves from Locality 106, Middle Cambrian shaly sandstones of the Rome formation, in Bays Mountains, 10 miles (16.1 km.) southeast of Knoxville, Tennessee. U.S. Nat. Mus. Cat. Nos. 27367a and 27367b, respectively. 3b. Cast of the interior of a ventral valve from Locality 10a, Middle Cambrian, at the same general locality as the specimens represented by figures 3 and 3a. U.S. Nat. Mus. Cat. No. 27326a. 3c and 3d. Casts of the interior of dorsal valves associated with the ventral valves represented by figures 3 and 3a. U.S. Nat. Mus. Cat. Nos. 27367c and 27367d, respectively. ~I a PL, XXI MONOGRAPH LI U, S. GEQLOGICAL SURVEY FRANCES WIESER DEL. ELIOTYPE CO, BOSTON PLATE XXI. a LINGULELLA (LINGULEPIS) ROWEI (Walcott) (p. 558). Ficure 4. Exfoliated ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 51897a. 4a, Exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 51897b. 4b. Enlargement of the outer surface of another specimen. U.S. Nat. Mus. Cat. No. 51897c. The three specimens from which figures 4, 4a—b are drawn are from Locality 14p, Lower Cambrian limestone near Resting Springs, Inyo County, California. LINGULELLA RANDOMENSIS (Walcott) (p. 530). Figure 5. Ventral valve, the type specimen, showing the cast of the area and pedicle groove. U.S. Nat. Mus. Cat. No. 35208a. 5a. Dorsal valve associated with specimen represented by figure 5. U.S. Nat. Mus. Cat. No. 35208b. The specimens represented are both from Locality 6y, Upper Cambrian, on the north side of Random Island, be- tween Birch and Sandy points, Smith Sound, Trinity Bay, Newfoundland. LINGULELLA SCHUCHERTI (Walcott) (p. 530). Ficure 6. Cast of a ventral valve, the type specimen, showing the area and pedicle furrow, from Locality 367, Lower Cambrian limestone, Troy, Rensselaer County, New York. U.S. Nat. Mus. Cat. No. 51775a. Paes Osi 4 ne TA Sale PLATH XXII. a. Central lateral space of area. i. Transmedian muscle scar. a’. Outer lateral space of area. j- Anterior lateral muscle scar. e. Trapezoidal area, including central, middle ps. Parietal band. lateral, and outside lateral muscle scars. vy. Visceral cavity. f. Flexure line of area. vs. Main vascular sinus. h. Central muscle sear. x. Heart-shaped cavity. LINGULELLA GRANVILLENSIS Walcott (p. 504). Ficure 1. Exterior of partly exfoliated ventral valve from Locality 38a, Lower Cambrian limestone, 2 miles south of North Granville, Washington County, New York. U.S. Nat. Mus. Cat. No. 17440a. Type speci- men, figured by Walcott [1887, Pl. I, fig. 15b; and 189la, Pl. LXVII, fig. 4b]. The specimen figured by Walcott [1887, Pl. I, fig. 15c; and 1891la, Pl. LX VII, fig. 4c] is not refigured in this mono- graph. It is in the collections of the United States National Museum, Catalogue No. 17440e. ja. Exterior of partly exfoliated ventral valve associated with the valve represented by figure 1. U.S. Nat. Mus. Cat. No. 17440b. 1b. Interior of a small ventral valve from Locality 37b, Lower Cambrian, one-fourth mile east of Salem, Wash- ington County, New York, showing the visceral cavity and main vascular sinuses. U.S. Nat. Mus. Cat. No. 52036a. lc. Exterior of a partly exfoliated dorsal valve associated with the valve represented by figures 1 and la. U.S. Nat. Mus. Cat. No. 17440c. Specimen figured by Walcott [1887, Pl. I, fig. 15; and 1891a, Pl. LXVII, fig. 4]. 1d. Cast of the interior of a dorsal valve associated with the valves represented by figures 1, la, and 1c, showing the visceral area with its muscle scars, and an unusually complex system of vascular canals. U.S. Nat. Mus. Cat. No. 17440d. Specimen figured by Walcott [1887, Pl. I, fig. 15a: and 1891a, PI. LXVII, fig. 4a]. OBOLUS LAMBORNI (Meek) (p. 393). Fieure 2. Interior of a flattened ventral valve from Locality 11j, Middle Cambrian shale at Mine Lamotte, Madison County, Missouri. U.S. Nat. Mus. Cat. No. 51553a. 2a. Cast of the interior of a ventral valve associated with the valve represented by figure 2. U.S. Nat. Mus. Cat. No. 51553b. 2b. Very fine cast of the interior of a ventral valve from Locality 121, Middle Cambrian Rogersville shale, road just east of Harlan Knob, 4 miles northeast of Rogersville, Hawkins County, Tennessee. U. S. Nat. Mus. Cat. No. 51558a. 2c. Cast of the interior of a ventral valve associated with the specimen represented by figure 2b, which has very much the same appearance as the specimen represented by figure 2a from the shale in Missouri. U.S. Nat. Mus. Cat. No. 51558b. 2d. Cast of the outer surface of a ventral valve associated with the valves represented by figures 2b and 2c, showing the strong concentric striz and fine radiating strie. U.S. Nat. Mus. Cat. No. 51558c. 2e and 2f. Casts of the interior of compressed ventral valves associated with those represented by figures 2b-d, illustrating variation in form, figure 2f being the result of distortion. U.S. Nat. Mus. Cat. Nos. 51558d and 51558e, respectively. 2g and 2h. Very fine interior casts of dorsal valves associated with the ventral valves illustrated by figures 2b-f. The variation in the character of the inner surface is well illustrated by these two figures; in figure 2h there are only faint indications of papille, while in figure 2¢ they are abundant. U. 8S. Nat. Mus. Cat. Nos. 51558f and 51558g, respectively. The area of figure 2h is represented in figure 2m. 2i aad 2j. Casts of the interior of two dorsal valves associated with the two ventral valves represented by figures 2 and 2a, at Locality 11j, near Mine Lamotte, Missouri. U.S. Nat. Mus. Cat. Nos. 51553¢ and 51553d, respectively. Figure 2] represents the type specimen. 2k. Cast of a dorsal valve associated with the valves represented by figures 2b-h (Locality 121), that illustrates variation in form. U.S. Nat. Mus. Cat. No. 51558h. 21. Cast of large dorsal valve from Locality 124a, Middle Cambrian shales on Big Creek, southeast of Harlan Knob, 4 miles northeast of Rogersville, Hawkins County, Tennessee. U.S. Nat. Mus. Cat. No. 51557a. 2m. Enlargement and partial restoration of the area of the dorsal valve represented by figure 2h. U.S. Nat. Mus. Cat. No. 515582. 2n. Cast of a dorsal valve associated with the valves represented by figures 2b-h. U.S. Nat. Mus. Cat. No. 515581. 80 U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XxII FRANCES WIESER DEL. HELIOTYPE CO BOSTON Per ean PLATE XXIII. a. Central lateral space of area. j. Anterior lateral muscle sear. a’. Outer lateral space of area. p. Pedicle groove. . f, Plexure lines of area. s. Median septum. h. Central muscle sear. vy. Visceral cavity. i. Transmedian muscle sear. vs. Main vascular sinus. Osotus wituist (Walcott) (p. 420). FicurE 1. Cast of a ventral valve, the type specimen, compressed in shale, Locality 140a, Middle Cambrian, near Cave Spring, Floyd County, Georgia. U.S. Nat. Mus. Cat. No. 27345a. la. Cast of a ventral valve compressed in shale, Locality 107b, Middle Cambrian, near Copper Ridge, 11 miles northwest of Knoxville, Tennessee. U.S. Nat. Mus. Cat. No. 27343a. 1b. Cast of a ventral valve compressed in shale, that shows the pitted or punctate character of the interior of the shell. Same locality as specimen represented by figure la. U.S. Nat. Mus. Cat. No. 273438b. le. Cast of the outer surface of a ventral valve, from same band of shale as specimen represented by figure la. U.S. Nat. Mus. Cat. No. 27348c. 1d. Cast of the outer surface of a dorsal valve associated with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 27343d. le. Cast of a ventral valve distorted by compression in the same band of shale as the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 27343e. li. Cast showing part of a ventral valve, the outline of which ‘is restored from associated specimens. It occurs in the calcareous sandstone embedded in the shales of Locality 107b, Middle Cambrian, near Copper Ridge, 11 miles northwest of Knoxville, Tennessee. U.S. Nat. Mus. Cat. No. 27343f. lg. Cast of the interior of a dorsal valve associated with the specimen represented by figure lf. U.S. Nat. Mus. Cat. No. 27348¢. th. Cast of the interior of a dorsal valve associated with specimen represented by figure 1f but which is more transverse. U.S. Nat. Mus. Cat. No. 27343h. li. Distorted cast of a ventral valve from Locality 101b, Middle Cambrian shale 3.5 miles southwest of Rogers- ville, Tennessee. U.S. Nat. Mus. Cat, No. 27344a. 1j. Flattened ventral valve, showing the strong interrupted radiating lines and the strong concentric rugose lines of growth. Locality 93, Upper Cambrian shale, near Jordans on Cowan Creek, Cherokee County, ‘Alabama. U.S. Nat. Mus. Cat. No. 27346a. LINGULELLA TARPA (Walcott) (p. 534). Fiaure 2. Exfoliated ventral valve from sandy shales, which shows general outline and some of the markings of the interior of the shell. U.S. Nat. Mus. Cat. No. 27342a. 2a. Compressed, slightly distorted ventral valve, the type specimen, from argillaceous shales interbedded with the sandy shales in which¢the specimen represented by figure 2 occurs. U.S. Nat. Mus. Cat. No. 27342b. 2b. Cast of a dorsal valve, from calcareous layers in the sandy shale in which specimen represented by figure 2 occurs. U.S. Nat. Mus. Cat. No. 27342c. 2c. Somewhat more elongate shell than that represented by figure 2b, with which it is associated, and which is somewhat doubtfully identified as a dorsal valve. U.S. Nat. Mus. Cat. No. 27342d. The specimens represented are all from Locality 11, Middle Cambrian, 1 mile east of Post Oak Springs, Roane County, Tennessee. OBOLUS MCCONNELLI (Walcott) (p. 396). Ficure 3. Interior of a crushed and broken ventral valve, the type specimen, from Locality 14s, Middle Cambrian Ogygopsis zone on Mount Stephen, British Columbia. U.S. Nat. Mus. Cat. No. 51572a. 3a. Interior of an associated fragmentary ventral valve of the broad form. U.S. Nat. Mus. Cat. No. 51572b. Copied from Walcott [1908c, Pl. I, fig. 2]. (See note under fig. 3d, below.) OBOLUS MCCONNELLI PELIAS (Walcott) (p. 398). (Pl. XXXIX, figs. 5, 5a-c.] Figure 3b. Interior of a broad form of dorsal valve, the type specimen, from Locality 11q, Middle Cambrian Marjum limestone, ridge east of Wheeler Amphitheater, House Range, Utah. U.S. Nat. Mus. Cat. No. 51592a. 3c. Interior of an associated dorsal valve. U.S. Nat. Mus. Cat. No. 51592b. 82 PL. XXill MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. HELIOTYPE CO BOSTON ip PLATE XXIII. 83 OxBo.Lus SEPrALIS (Walcott) (p. 414). (Pl. XXXIV, figs. 2, 2a.) Fieure 3d. Dorsal valve from Locality 14s, Middle Cambrian Ogygopsis zone on Mount Stephen, British Columbia. U.S. Nat. Mus. Cat. No. 24069a. Copied from Walcott [1908c, Pl. I, fig. 2a], where it was figured as Obolus mcconnelli. OBOLUS MCCONNELLI DECIPIENS Walcott (p. 398). Fiaure 4. Compressed ventral valve, the type specimen, from Locality 7v, Upper Cambrian shales 4.25 miles south- southeast of Emigrant Peak, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 51586a. 4a. Compressed ventral valve from Locality 8m, Middle Cambrian limestone 4 miles northeast of Osceola, White Pine County, Nevada. U.S. Nat. Mus. Cat. No. 51585a. : 4b. Ventral valve associated with specimen represented by figure 4a. U.S. Nat. Mus. Cat. No. 51585b. OxsoLus FRAGILIS (Walcott) (p. 392). Ficure 5. Cast of the interior of a ventral valve, the type specimen, from Locality 1, Middle Cambrian shales on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 27317a. 5a. Dorsal valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 27317b. 5b. Outline of the dorsal valve, showing area, from Locality 2, Middle Cambrian shale from a higher horizon than that represented by figure 5, on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 56911a. 5c. Cast of the interior of a dorsal valve associated with the specimen represented by figure 5. U.S. Nat. Mus. Cat. No. 27317c. 5d. Cast of the interior of a dorsal valve, showing concentric and radiating striz, associated with specimen represented by figure 5b. U.S. Nat. Mus. Cat. No. 56911b. 5e. Broad dorsal valve associated with specimen represented by figure 5. U.S. Nat. Mus. Cat. No. 27317d. ns} a | Pin eave 7 . PLATE XXIV. . Pedicle groove. . Median septum. . Visceral cavity. . Main vascular sinus. a. Central lateral Space of area. a’. Outer lateral space of area. . Flexure line of area. . Central muscle scar. . Anterior Jateral muscle scar. adutd i=7 Pay coo LINGULELLA NANNO (Walcott) (p. 521). Ficures 1 and la. Ventral valves, preserving natural form and convexity, from Locality 16, Middle Cambrian limestones in Blountsville Valley, Blount County, Alabama. U.S. Nat. Mus. Cat. Nos. 27328a and 27328b, respectively. Figure la represents the type specimen. 1b and 1c. Dorsal valves associated with the specimens represented by figures 1 and la. U.S. Nat. Mus. Cat. Nos. 27328¢ and 27328d, respectively. id. Unusually large and convex dorsal valve from Locality 91, Middle Cambrian limestone at Cedar Bluff, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 57005a. LINGULELLA LEOS (Walcott) (p. 513). Fieure 2. Partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 27323a. 2a. Cast of the interior of a ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 27323b. 2b and 2c. Casts of interior of two dorsal valves. 2c is strongly convex and unusually narrow and elongate. U.S. Nat. Mus. Cat. Nos. 27323c and 27323d, respectively. The specimens represented are all from Locality 96, Upper Cambrian limestone, 1.5 miles south of Rome, Floyd County, Georgia. LINGULELLA HELENA (Walcott) (p. 506). Figure 3. Exterior of a slightly distorted ventral valve from Locality 302s, Middle Cambrian siliceous shale 1.5 miles south of Helena, Lewis and Clark County, Montana. U.S. Nat. Mus. Cat. No. 27320a. 3a and 3b. Casts in siliceous shale of the interior of two ventral valves that differ in outline, from the locality represented by figure 3. U.S. Nat. Mus. Cat. Nos. 27320b and 27320c, respectively. Figure 3a represents the type specimen. 3c. Cast of the interior of a dorsal valve showing area, from the locality represented by figure 3. U.S. Nat. Mus. Cat. No. 27320d. 3d. Small ventral valve doubtfully referred to the species, from Locality 30a, Middle Cambrian shale in Big Cottonwood Canyon, near Salt Lake City, Utah. U.S. Nat. Mus. Cat. No. 51819a. LInGULeLia puBIA (Walcott) (p. 494). Ficure 4. Cast of interior of ventral valve, the type specimen, associated with Obolus ( Westonia) ella at Locality 31, Middle Cambrian shales at Pioche, Nevada. U.S. Nat. Mus. Cat. No. 2731]4a. 4a. Cast of interior of dorsal valve on same piece of shale with the specimen represented by figure 4. U.S. Nat. Mus. Cat. No. 27314b. LINGULELLA AaRGUTA (Walcott) (p. 478). Figure 5. Perfect ventral valve, the type, from Locality 318f, Upper Cambrian limestone at Schellbourne, Schell Creek Range, Nevada. U.S. Nat. Mus. Cat. No. 273805a. Drawn from specimen represented by White [1877, Pl. III, fig. 2a] as Lingula? manticula. 5a. Dorsal valve that is doubtfully referred to this species from Locality 318a, Middle Cambrian limestone at Schellbourne, Nevada. U.S. Nat. Mus. Cat. No. 51845a. : 5b. Partly exfoliated dorsal valve from Locality 10y, Middle Cambrian Marjum limestone, near Marjum Pass, House Range, Utah. U.S. Nat. Mus. Cat. No. 58303. 86 XI\ PL. X MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DE BOSTON HELIOTYPE co eer TPAD ANAND) OXON. 87 LINGULELLA AUGA (Walcott) (p. 480). Fieures 6 and 6a. Casts in shaly limestone of interior of two ventral valves. U.S. Nat. Mus. Cat. Nos. 27306a and 27306b, respectively. 6b. Cast of the posterior portion of the interior of a distorted ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 27306c. 6c. Cast of the posterior portion of the interior of a ventral valve, showing a trace of the visceral area. U.S. Nat. Mus. Cat. No. 27306d. 6d and 6e. Casts of the interior of two dorsal valves. U.S. Nat. Mus. Cat. Nos. 27306e and 27306f respectively. The specimens illustrated by figures 6, 6a-e are from Locality 10a, Middle Cambrian shaly sandstones at Shooks Gap, 10 miles southeast of Knoxville, Tennessee. Fieures 6f and 6g. Ventral and dorsal valves from Locality 10b, a siliceous limestone interbedded in the Middle Cambrian shaly sandstones at Shooks Gap, 10 miles southeast of Knoxville, Tennessee. The outer surface with strong concentric striz is finely preserved. U.S. Nat. Mus. Cat. Nos. 27306g and 27306h, respectively. LINGULELLA TUMIDA Matthew (p. 537). Figure 7. Exterior of ventral valve from Locality 18i, Middle Cambrian sandy shales on Gillis Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51769a. 7a. Cast of the interior of a ventral valve associated with the shell represented by figure 7, showing the high area and strong vascular sinuses. U.S. Nat. Mus. Cat. No. 51769b. 7b. Cast of the interior of a ventral valve from Locality 18r, a little different horizon from that represented by Locality 138i, Middle Cambrian sandy shales on Gillis Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 57011a. 7c. Exterior of ventral valve associated with the shell represented by figure 7. U.S. Nat. Mus. Cat. No. 51769c. : 7d. Cast of the interior of a ventral valve associated with the shell represented by figure 7b, retaining a portion of the shell on the umbo. U.S. Nat. Mus. Cat. No. 57011b. PLATE XXV, PLATE XXV. a. Central lateral space of area. p. Pedicle groove. a’. Outer lateral space of area. ps. Parietal band. f. Flexure line of area. s. Median septum. h. Central muscle scar. v. Visceral cavity. i. Transmedian muscle scar. vs. Main vascular sinus. j. Anterior lateral muscle sear. LINGULELLA HAYESI (Walcott) (p. 505). Figure 1. Cast of the interior of a ventral valve, showing the area and portions of the visceral cavity. U.S. Nat. Mus. Cat. No. 27319}. la. Interior of a partly weathered ventral valve. U.S. Nat. Mus. Cat. No. 27319a. 1b and 1c. Casts of the interior of the ventral valve, showing the position of the main vascular sinuses, the visceral cavity, and the area. U.S. Nat. Mus. Cat. Nos. 27319b and 27319c, respectively. Figure 1b represents the type specimen. 1d. Enlargement of the cast of the area of the ventral valve, showing the pedicle groove, the flexure line, and the central and outer lateral spaces of the area. U.S. Nat. Mus. Cat. No. 27319d. le. Cast of the interior of a dorsal valve showing the position of the central (h) and anterior lateral (j) muscle scars, the scar of the parietal band (ps), also the arching forward of the center of the area. U.S. Nat. Mus. Cat. No. 27319e. lf, 1g, 1h, and li. Casts of the interior of dorsal valves, showing variation in form of the valve and in the posi- tion of the parietal band and main vascular sinus. The latter is especially well shown by figure 1g. U.S. Nat. Mus. Cat. Nos. 27319f, 27319¢, 27319h, and 27319i, respectively. 1j. Enlargement of the area of the dorsal valve represented by figure 1f. U.S. Nat. Mus. Cat. No. 27319f. All of the specimens represented occur on the exterior of siliceous nodules, or on breaks across them, from Locality 90x, Middle Cambrian Conasauga shale, Coosa Valley, Cherokee County, Alabama. Opotus (WESTONIA) CHUARENSIS (Walcott) (p. 454). Figures 2 and 2a. Partly exfoliated ventral valves from Locality 78a, Middle Cambrian sandstone, Chuar Valley, Grand Canyon of the Colorado, Arizona, showing some variation in form. U.S. Nat. Mus. Cat. Nos. 57020a and 57020b, respectively. Figure 2 represents the type specimen. 2b. Crushed ventral valve from Locality 74b, Middle Cambrian sandstone in Nunkoweap Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 57021a. 2c. Exterior of a rather large dorsal valve from Locality 74, Middle Cambrian sandstone at the head of Nunko- weap Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 27310a. 2d. Cast of part of the interior of a dorsal valve associated with the shells represented by figures 2 and 2a, showing a median depression and the area. U.S. Nat. Mus. Cat. No. 57020c. 2e. Strongly marked cast of the interior of a dorsal valve associated with the shell represented by figure 2c, showing the depression filled by the ridges adjacent to the main vascular sinuses, a strong central grooye corresponding to the median septum, and the central muscle scars (h). U. S. Nat. Mus. Cat. No. 27310b. Oxpoivs zETUS (Walcott) (p. 421). Figures 3, 3a, and 3b. Partly exfoliated ventral valves, showing the external form and something of the character of the different layers forming the shell. U.S. Nat. Mus. Cat. Nos. 27347a, 27347b, and 27347c, respectively. Figure 3a represents the type specimen. 3c. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 27347d. The specimens represented are all from Locality 74, Middle Cambrian sandstone, near the head of Nunkoweap Valley, Grand Canyon of the Colorado, Arizona. OBOLUS LAMBORNI MINIMUS (Walcott) (p. 395). Ficures 4 and 4a. Casts of ventral valves that were compressed in the shale. U.S. Nat. Mus. Cat. Nos. 27322a and 27322b, respectively. Figure 4 represents the type specimen. 4b. Dorsal valve associated with the ventral valves represented by figures 4 and 4a. U.S. Nat. Mus. Cat. No. 27322c. The specimens illustrated are all from Locality 101a, Middle Cambrian Rogersville shale, 3.5 miles southwest of Rogersville, Hawkins County, Tennessee. 90 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XXV FRANCES WIESER DEL. HELIOTYPE CO BOSTON He Shh De eh 4 ide roe t PLATE Sov PLATE XXVI. ce. Trapezoidal area, including central, middle j. Anterior lateral muscle scar. lateral, and outside lateral muscle sears. m. Pedicle muscle. f. Flexure line of area. p. Pedicle groove. g. Umbonal muscle scar. s. Median septum. h. Central muscle scar. vy. Visceral cavity. i. Transmedian muscle scar. vs. Main vascular sinus. LINGULELLA PHAON (Walcott) (p. 525). Figure 1. Ventral valve from Locality 84a, Upper Cambrian sandstone at River Junction, Houston County, Minne- sota, the exterior of which has been slightly injured by abrasion. U.S. Nat. Mus. Cat. No. 27406a. la. Dorsal valve associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 27406b. lb. Strongly marked cast of the interior of a ventral valve from Locality 98x, Upper Cambrian sandstone near Eau Claire, Wisconsin. This specimen shows the broken edge of the undercut that extended back under the area and the deeply impressed character of the channels of the main vascular sinuses; also the large size of the pits or punctz on the interior of the shell. U.S. Nat. Mus. Cat. No. 27331a. lc. Cast of the interior of a ventral valve, the type specimen, associated with the specimen represented by fig- ure 1b, showing more definitely the interior features of the shell. The divided umbonal muscle scars and the pedicle muscle scar are drawn from an associated ventral valve. The central, middle lateral, and outside lateral muscle scars are not differentiated in the deeply impressed trapezoidal area (c); the anterior lateral muscle scars (j) are well shown. U.S. Nat. Mus. Cat. No. 27331b. 1d. Interior cast of a dorsal valve associated with the specimen represented by figure 1b, having the same strongly marked characteristics as the casts of the ventral valve. The cast of the central ridge is very pronounced, and it is difficult to say just where the central muscle scars (h) were located. They appear to be, however, as indicated on the drawing, which brings them very close to the small anterior lateral scars. U.S. Nat. Mus. Cat. No. 27331c. le. Interior cast of a very strongly marked dorsal valve associated with the specimen represented by figure 1b, in which the detailed characters are lost. The general effect of this cast is much like that of the interior cast of the dorsal valve of eee grandis (Pl. XX XVIII, fig. 2d). U.S. Nat. Mus. Cat. No. 27331d. OxsoLus sINoE (Walcott) (p. 415). Ficur® 2. Interior cast of a ventral valve. U.S. Nat. Mus. Cat. No. 2734la. 2a. Interior of a ventral valve preserving the area and showing the undercut beneath the area. The impres- sions of the visceral cavity are indistinct. U.S. Nat. Mus. Cat. No. 27341b. Another specimen (Cat. No. 27341c) was used to restore parts of the drawing. 2b. Cast of the interior of a ventral valve, showing a portion of the shell and the posterior portion of the main vascular sinuses. U.S. Nat. Mus. Cat. No. 27341d. 2c. Dorsal valve from which the exterior layer has been remov el so as to show the edges of the oblique interior lamelle. U.S. Nat. Mus. Cat. No. 2734le. 2d. Cast showing part of the interior of a ventral valve. U.S. Nat. Mus. Cat. No. 27341f. The specimens represented by figures 2, 2a—d are from Locality 68y, Upper Cambrian reddish brown sandstone on Packsaddle Mountain, Llano County, Texas. Figure 2e. Cast of an interior of a ventral valve. The strongly marked channel of the parietal scar and the elevated ridge in front of it is very characteristic of Obolus apollinis (Pl. VII). The posterior portion toward the area is restored from a second specimen. U.S. Nat. Mus. Cat. No. 51627a. 2f. Cast showing part of the interior of a dorsal valve, the type specimen. The anterior lateral scars are well shown on another specimen. U.S. Nat. Mus. Cat. No. 51627b. 2g. An elongate dorsal valve preserving the outer surface of the shell. U.S. Nat. Mus. Cat. No. 51627c. 2h. Enlargement of the anterior portion of a shell to illustrate the oblique lamellz forming the strong shell. U.S. Nat. Mus. Cat. No. 51627d. : The specimens represented by figures 2e-h are from Locality 70, Upper Cambrian limestone near Morgans Creek, Burnet County, Texas. 92 PL. XXVI MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. BOSTOK HELIOTYPE CO : Poe PATE, XeXvi, 93 LINGULELLA FRANKLINENSIS (Walcott) (p. 501). Freure 3. Somewhat crushed ventral valve, the type, from which most of the shell has been exfoliated. Locality 87, Lower Cambrian limestone near Highgate Falls, Franklin County, Vermont. U.S. Nat. Mus. Cat. No. 27318a. 3a. Dorsal (?) valve from the locality represented by figure 3, preserving the outer surface. This may be, how- l ever, a distorted ventral valve. U.S. Nat. Mus. Cat. No. 27318b. 3b. Largest ventral valve in the collection. Locality 28a, Middle ? Cambrian, near Parker’s quarry, Georgia, Vermont. U.S. Nat. Mus. Cat. No. 52454a. LINGULELLA INO (Walcott) (p. 507). Fieure 4. Cast of the interior of a ventral valve, the type specimen, showing somewhat imperfectly the visceral cavity and main vascular sinuses. U.S. Nat. Mus. Cat. No. 2732la. 4a. Ventral valve preserving a portion of the shell, showing the area, pedicle groove, and flexure lines very clearly. U.S. Nat. Mus. Cat. No. 27321b. 4b. Cast of the interior of a dorsal valve, showing a relatively large area and portions of the shell adhering to the cast. U.S. Nat. Mus. Cat. No. 27321c. The specimens represented are all from Locality 18b, Middle Cambrian sandstones northeast of Rhea Springs, Roane County, Tennessee. PLATE XXVII. c. Trapezoidal area, including central, middle j. Anterior lateral muscle sear. lateral, and outside lateral muscle sears. m. Pedicle muscle. g. Umbonal muscle scar. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. LINGULELLA PRIMA (Conrad MS.) (Hall) (p. 526). Fiavre 1. Cast of the interior of a ventral valve, showing the pestle-shaped ridge that filled the median groove of the interior of the shell. U.S. Nat. Mus. Cat. No. 27435a. la. Exterior ofa ventral valve, showing rather strong undulations of growth. U.S. Nat. Mus. Cat. No. 27435 1b. Fragment of a ventral valve, showing the cast of the area, the divided umbonal muscle scar (g), and the pedicle scar (m). U.S. Nat. Mus. Cat. No. 27435c. lc. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 27435d. The specimens represented are all from Locality 77, Upper Cambrian sandstone, Ausable Chasm, Essex County, New York. LINGULELLA Iris (Billings) (p. 509). Fictre 2. Dorsal valve, the type specimen, from Locality 319d, Upper Cambrian, Point Levis, Quebec, Canada. Geol. Survey Canada. Redrawn from the specimen described and figured by Billings [1865a, p. 301, fig. 290] as Lingula iris. OBOLUS PRINDLEI (Walcott) (p. 409). Figure 3. Ventral valve, the type, from Locality 72a, Lower Cambrian, 1 mile southwest of Wynantskill, Rensselaer County, New York, showing the character of the outer surface and also of the surface of the inner layers where the shell is exfoliated over its umbonal portion. U.S. Nat. Mus. Cat. No. 27333a. 34. Cast of the interior ofa ventral valve which is broken away a little at the beak. This specimen is associated on the same hand specimen with the valve represented in figure 3. U.S. Nat. Mus. Cat. No. 27333b. 3b. Portion ofa ventral valve from Locality 72a, Lower Cambrian, 1 mile southwest of Wynantskill, Rensselaer County, New York, showing the cast of the finely punctate inner surface and the peculiar lamellose- like strize of growth upon the area. U.S. Nat. Mus. Cat. No. 27333c. 3c. Cast of the interior of a dorsal valve, associated on the same hand specimen with the valve represented by figure 3, showing the area. U.S. Nat. Mus. Cat. No. 27333d. 3d. Exterior of a dorsal valve from Locality 72, Lower Cambrian limestone 5 miles west of Albany, Rensselaer * County, New York, illustrating the character of the outer surface. U.S. Nat. Mus. Cat. No. 27334a. 3e. Cast of the interior of a dorsal valve that is more convex and more oval in outline than the specimen repre- sented by figure 3, which is associated on the same hand specimen with it. U.S. Nat. Mus. Cat. No. 27333e. OBoLus CYANE (Billings) (p. 388). Fievre 4. Cast of the interior of a ventral valve, the type specimen, which preserves a portion of the inner layers of the shell over the visceral area. 4a, Imperfect cast of a ventral valve, showing the lamellated shell structure. 4). Cast of the interior ofa dorsal valve. The muscle scars are obscured in the specimen from which the figure has been drawn, and those that appear in the figure are from another specimen occurring in the same fragment of limestone. ‘ The specimens represented are all from Locality 314d, Lower Ordovician limestone 4 miles northeast of Portland Creek. Newfoundland, and are now in the collections of the Geological Survey of Canada. These specimens were illustrated by Billings [1865a, figs. 20a-d, p. 215], but further identification of his figures with those in this monograph is impossible. LINGULELLA IOLE (Billings) (p.:508). Ficures 5 and 5a. Ventral and dorsal valves, respectively, from Locality 314d, Lower Ordovician limestone 4 miles northeast of Portland Creek, Newfoundland. Geol. Survey Canada. Redrawn from the two speci- mens figured by Billings [1865a, figs. 199a-e, p. 215] as Lingula iole. The ventral may be taken as the type. 96 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL, XXVII FRANCES WIESER DEL. HELIOTYPE CO in itn hy ne PLATH XXVII. 97 LINGULELLA IRENE (Billings) (p. 508). Ficure 6. Interior of a flattened ventral valve, preserving the area and portions of the shell. The concentric striation of the exterior of the shell is shown at the place where the shell is broken away. 6a. Partly exfoliated outer surface of a dorsal valve that is compressed in the shale. The specimens represented are both from Locality 813a, Lower Ordovician Levis shale at Point Levis, Quebec, Canada, and are in the collection of the Geological Survey of Canada. They were described and figured by Billings [1862d, pp. 71-72, figs. 64a—b] as Lingula irene. Figure 6 may be taken as the type. LINGULELLA CUNEOLA (Whitfield) (p. 488). Fieure 7. Cast of a ventral valve from Locality 355, Middle Cambrian sandstone, Red Canyon Creek, Black Hills, South Dakota. U.S.Nat. Mus. Cat. No 24587a. Type specimen, figured by Whitfield [1880, Pl. I, fig. 6] as Lingulepis cuneolus. The specimen figured by Whitfield [1880, Pl. I, fig. 5] is not figured in this monograph. _ 7a. Cast of the interior of a ventral (?) valve, associated with the valve represented by figure 7, preserving a portion of the shell on the outer margins. U.S. Nat. Mus. Cat. No. 33873a. 7b. Cast of the interior of a dorsal valve, associated with specimens represented by figures 7 and 7a. U.S. Nat. Mus. Cat. No. 33873b. 62667°—vo1 51, pr 2—12——7 Rear sya I, OC Pane PLATE XXVIII. a. Central lateral space of area. p. Pedicle groove. a’. Outer latera! space of area. s. Median septum. f. Flexure line of area. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. i. Transmedian muscle scar. y- See text (p. 478). j. Anterior lateral muscle scar. LINGULELLA AMPLA (Owen) (p. 477). Fieure 1. Ventral valve partly broken away near the apex, from Locality 339e, Middle Cambrian sandstone on Mountain Island, Minnesota. U.S. Nat. Mus. Cat. No. 17859b. Type specimen, figured by Owen [1852, Pl. IB, fig. 5] as Lingula ampla. The specimen represented by figure 12 of the same plate (Catalogue No. 17859a) is not figured in this monograph. la. Ventral valve, from Locality 84s, Middle Cambrian sandstone near Dakota, Winona County, Minnesota. U.S. Nat. Mus. Cat. No. 35241a. 1b. Dorsal valve, associated with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 35241b. Ic. Cast of the interior of a ventral valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 35241c. ? 1d. Cast of the interior of the ventral valve represented in figure 1f, enlarged. Locality 84s, Middle Cambrian sandstone near Dakota, Winona County, Minnesota. U.S. Nat. Mus. Cat. No. 35241d. le. Cast of the interior of the posterior portion of a ventral valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 35241e. 1f. Cast of the interior of a ventral valve showing an unusual feature at y. This specimen is enlarged in figure ld. U.S. Nat. Mus. Cat. No. 35241d. 1g. Cast of the interior of a dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 35241f. th. Cast of the interior of a dorsal valve associated with the specimen represented by figure la. U.S. Naw. Mus. Cat. No. 35241g. li. Enlargement of the area shown in figure lh. U.S. Nat. Mus. Cat. No. 35241¢. 1j. Ventral valve tentatively referred to this species, from Locality 88a, Middle Cambrian limestone at Dead- wood, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 51784a. Opotus (WESTONIA) sTONEANUS (Whitfield) (p. 465). [Pl. XLIX, figs. 2 and 2a.] Figure 2. Cast of the interior of a compressed ventral valve. U.S. Nat. Mus. Cat. No. 51727a. 2a. Cast of the interior of a ventral valve, showing a few traces of the interior markings of the shell. U.S. Nat. Mus. Cat. No. 51727b. 2b. Enlargement of a cast of the area of a ventral valve. U.S. Nat. Mus. Cat. No. 51727c. 2c. Cast of the posterior portion of the interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51727d. 2d. Enlargement of a portion of the outer surface of a ventral valve. U.S. Nat. Mus. Cat. No. 51727e. 2e. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51727f. 2f. Posterior half of a cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51727g. 2e. Cast of the outer surface of a dorsal valve. U.S. Nat. Mus. Cat. No. 51727h. The specimens represented are all from Locality 85s, Upper Cambrian sandstone at Prairie du Sac, Sauk County, Wisconsin. 100 PL. XXVIII MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. STON co ac HELIOTYPE Gy bra Ny i Ryne och at Ahan o Pitino bats Pe nme eel) OXOXGIDXS 101 PGA, XOXX. h. Central muscle scar. s. Median septum. i. Transmedian muscle scar. vy. Visceral cavity. j. Anterior lateral muscle scar. vs. Main vascular sinus. LINGULELLA FERRUGINEA Salter (p. 496). [PI. XXX, fig. 1; Pl. XX XI, figs. 3, 3a-c; and Pl. XXXYV, figs. 4, 4a-b.] Figure 1, Cast of the interior of a ventral valve compressed in the shale of Division lc of Matthew [1886, p. 82], in New Brunswick (locality not given). University of Toronto, Canada. Specimen figured by Matthew [1886, Pl. V, fig. 9d] as Lingulella dawsoni. Ja. Ventral and dorsal valves from Locality 3011, Middle Cambrian shales of Division 1d of Matthew on Porters Brook, St. John County, New Brunswick. University of Toronto, Canada. Specimens figured by Matthew [1886, Pl. V, figs. 8, 8a—b] as Lingulella linguloides. 1b and le. Ventral and dorsal valves shown in figure la. University of Toronto, Canada. 1d. Ventral valve from Locality 391k, Middle Cambrian, St. John formation in St. John, New Brunswick. Cornell University, Ithaca, N. Y. Specimen figured by Walcott [1884a, Pl. V, fig. 8] as Lingula ? dawsoni. le. Small exfoliated ventral valve from Locality 1a, Middle Cambrian shale on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51757a. lf. Distorted ventral valve from Locality 2, Middle Cambrian shales on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 56997a. lg. Cast of the exterior of a distorted ventral valve, associated with the specimen represented by figure If. U.S. Nat. Mus. Cat. No. 56997b. 1h. Interior of part of a dorsal valve, associated with specimen represented by figure If. U.S. Nat. Mus. Cat. No. 56997c. li. Slightly distorted dorsal valve associated with specimen represented by figure 1f. U.S. Nat. Mus. Cat. No. 56997d. 1j. Unusually convex and well-preserved ventral valve associated with specimen represented by figure 1f. U.S. Nat. Mus. Cat. No. 56997e. 1k. Exfoliated, slightly distorted ventral valve, associated with specimen represented by figure lf. U.S. Nat. Mus. Cat. No. 56997f: Sea 11. Partly exfoliated ventral valve from the limestones interbedded in the shales of Locality 1, Middle Cambrian, Manuels Brook, Conception Bay, Newfoundland. The peculiar appearance of what is shown of the interior of the shell is partly explained by figure lo, which is compressed in the shale. U.S. Nat. Mus. Cat. No. 51756c: Im. Ventral valve, associated with specimen represented by figure 11. A portion of the outer surface is” exfoliated so as to show the characteristic markings of the inner surface. U.§8. Nat. Mus. Cat. No. 51756d. In. Cast of a dorsal valve showing the cast of a median septum and area, from Locality 1a, Middle Cambrian sandy shale 50 feet lower in the section than specimens represented by figures 1] and lm, on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51757b. lo. Cast of the interior of a ventral valve showing the area of a portion of the visceral cavity. From Locality 1, Middle Cambrian shale, Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51756a. : 1p. Very nearly perfect dorsal valve, associated with the specimen represented by figure 11. U.S. Nat. Mus. Cat. No. 51756e. lq. Cast of the interior of a dorsal valve associated with the specimen represented by figure 1]. U.S. Nat. Mus. Cat. No. 517568. ; lr. Interior of a dorsal valve, showing vascular sinus and median septum; also the ridges bounding the path of advance of the central scars. Associated with the specimen represented by figure 11. U.S. Nat. Mus. Cat. No. 51756g. 1s. Cast of the interior of a dorsal valve from Locality 1, Middle Cambrian shale on Manuels Brook, Concep- tion Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51756b. lt. Ventral valve, laterally compressed, preserving the fine surface markings described in the text. Collected from Locality 6g, Middle Cambrian limestone, Chapple Arm, Trinity Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51759a. lu. Cast showing part of the interior of a ventral valve from Locality 308, Upper Cambrian shales of Division C3e of Matthew’s section at Navy Island, St. John Harbor, New Brunswick. University of Toronto. The specimen represented by figure 1u was illustrated by Matthew [1892, Pl. XII, fig. 8b] as Obolella? gemmula. 102 RAPH L G NOC MO GEOLOGICAL SURVEY Ss. U, FRANCES WIESER DEL, PVA NONE: 103 LINGULELLA FERRUGINEA Salter—Continued. Ficure ly. Cast showing part of the interior of a dorsal valve associated with the specimen represented by figure lu, The outlines of a pedicle groove were produced by accidental fractures in the shell. U niversity of Toronto. Specimen illustrated by Matthew [1892, Pl. XII, fig. 8c] as Obolella? gemmula. lw. Compressed ventral valve associated with Obolus refulgens in Locality 308, Upper Cambrian shales of Division C3c of Matthew’s section, Navy Island, St. John Harbor, New Brunswick. University of Toronto. 2. Ventral ? valve from Locality 318h, Middle Cambrian shales at St. Davids, South Wales. Copied from Hicks’s figure [Salter and Hicks, 1867, fig. 2, p. 340] of Lingulella ferruginea ovalis. 2a. Enlarged view of the valve represented by figure 2. Copied from Salter and Hicks [1867, fig. 3, p. 340]. 2b. Ventral valves from Locality 318j, Middle Cambrian at Pen-y-pleidiau, St. Davids, South Wales. Copied from Salter’s figure [Salter and Hicks, 1867, fig. 1, p. 340] of Lingulella ferruginea.. It represents the type specimen. 2c. Ventral? valve from Locality 318v, Upper Cambrian, Rhiwfelyn, North Wales. Copied from Davidson [1868, Pl. XV, fig. 7a]. 2d. Ventral valve from Locality 318u, Upper Cambrian, Gwerny-y-Barcud, North Wales. Copied from David- son [1868, Pl. XV, fig. 6a]. 2e. Distorted ventral valve from Locality 366b, Middle Cambrian at Porthclais Harbor, south of St. Davids, South Wales. Copied from Davidson [1871, Pl. XLIX, fig. 35a]. 2f. Distorted ventral valve from Locality 318h, Middle Carabrian: Menevian shales at St. Davids, South Wales. Copied from Davidson [1871, Pl. XLIX, fig. 33a]. LINGULELLA BILLINGSIANA (Whiteaves) (p. 483). Figures 3 and 3a. Ventral valves, from Locality 314a, Upper Cambrian shales on Kelleys Island, Conception Bay, Newfoundland. Drawn from the type material in the Museum of the Geological Survey of Canada. , Whiteaves [1878, p. 226] did not figure the specimens on which he based his species. Figure 3a may be taken as the type. LINGULELLA Burtst Walcott (p. 484). Ficure 4, Dorsal valve, the type specimen, from Locality 90ce, Middle Cambrian Conasauga limestone near Kimbrel, Bibb County, Alabama, showing the slight median flattening of the surface and backward curvature of the concentric strie. U.S. Nat. Mus. Cat. No. 51779a. Copied from Walcott [1908d, Pl. VIII, fig. 6]. 4a and 4a’. Exterior view and side outline of ventral valve from Locality 90b, Middle Cambrian Conasauga limestone near Woodstock, Bibb County, Alabama. U.S. Nat. Mus. Cat. No. 51778a. 4b and 4b’. Partly exfoliated ventral valve associated with the shell represented by figure 4a, showing the cast of the ridges along the path of advance of the muscle scars on each side of the visceral area. U.S. Nat. Mus. Cat. No. 51778b. DELGADELLA LUsITANICA (Delgado) (p. 560). Ficure 5. Cast of the interior of a ventral valve, the type specimen. The marginal rim indicates the thickness of the shell. 5a. Cast of the interior of a ventral valve. 5b. Cast of a ventral valve. The specimens represented are all from Locality 351, Lower Cambrian shales at Monte de Valbom, northeast of Villa Boim, Province of Alemtejo, Portugal. The figures (5, 5a, and 5b) are reproduced from photographs sent to me by M. Delgado of the specimens figured by him [1904, Pl. LV, figs. 34, 31, and 32, respectively] under the name of Lingulepis lusitanica. Each of the views in this monograph is the reverse of the corresponding one given by Delgado. LINGULELLA DELGADOI WaALooTT (p. 491). Ficure 6. Cast of exterior of ventral valve, the type specimen. 6a. Cast of interior of ventral valve. Figures 6 and 6a are reproduced from photographs sent to me by M. Delgado of the specimens figured by him [1904, Pl. IV, figs. 16 and 18, respectively] under the name of Lingulella granvillensis. Figure 6b. Cast of dorsal valve showing exterior surface. Reproduced from a photograph sent to me by M. Delgado of the specimen figured by him [1904, Pl. IV, fig. 27] under the name of Lingulepis acuminata meek. The view in this monograph is the reverse of that given by Delgado. 6c. Cast of shell of dorsal valve partly broken away. Reproduced froma aetcerant sent to me by M. Delgado of the specimen figured by him [1904, Pl. IV, fig. 14] under the name of Lingulella cf. linguloides. The view in this monograph is the reverse of that given by Delgado. The specimens represented by figures 6, 6a-c are from Locality 351, Lower Cambrian shales at Monte de Valbom, northeast of Villa Boim, Province of Alemtejo, Portugal. ePAiny xeOOR : alta ~ 105 PLATE XXX. LINGULELLA FERRUGINEA Salter? (p. 496). [Pl. X XIX, figs. 1, la-w, 2, 2a-f; Pl. XX XI, figs. 3, 3a-c; and Pl. XXXV, figs. 4, 4a-b.] Figure 1. Ventral valves from Locality 389d, Upper Cambrian, at Iruya, Salta, Argentina. Copied from Kayser’s figure [1897, Pl. VII, fig. 7] of Lingulella cf. ferruginea. LINGULELLA pDAvist (McCoy) (p. 489). [Pl. XXXI, figs. 6, 6a-h.] Figure 2. Dorsal valve, from Locality 389d, Upper Cambrian, at Iruya, Salta, Argentina. Copied from Kayser [1897, Pl. VII, fig. 6]. 2a. Ventral and dorsal valves from Locality 332, Upper Cambrian limestone at Saimaki, Liaotung, China. Copied from Kayser [1883, Pl. III, fig. 3]. LINGULELLA NICHOLSONI Callaway (p. 522). Fieure 3. Ventral valve, the type specimen, from Locality 304i, Upper Cambrian Shineton shales in South Shrop- shire, England. Copied from Callaway [1877, Pl. XXIV, fig. 11]. 3a. Enlargement of the area of a ventral valve from one of the localities mentioned in Locality 304i, South Shropshire, England. Copied from Callaway [1877, Pl. XXIV, fig. 11b]. 3b. Dorsal valve with outer shell exfoliated except over the area. U.S. Nat. Mus. Cat. No. 51748a. 3c. Exfoliated dorsal valve. The central and transmedian muscle scars are drawn from another specimen. U.S. Nat. Mus. Cat. No. 51748b. 3d. A small ventral valve showing outline of area. U.S. Nat. Mus. Cat. No. 51748c. 3e. A small elongate dorsal valve. U.S. Nat. Mus. Cat. No. 51748d. 3f. A small ventral valve resting on the dorsal valve which has been pushed backward out of its natural position. U.S. Nat. Mus. Cat. No. 51748e. The specimens represented by figures 3b-f are from Locality 3041, Upper Cambrian Shineton shale, on Shineton Brook and vicinity, South Shropshire, England. LINGULELLA cf. FERRUGINEA (p. 500). Ficure 4. Ventral valve from Locality 345, Middle Cambrian shale on the Dlouhaé Hora, near Skrej, Bohemia. Copied from Pompeckj’s figure [1896b, Pl. XIV, figs. 16a—b] of “‘ Lingulella (?) sp.” LINGULELLA KIURENSIS (Waagen) (p. 511). Ficure 5. Type specimen of Waagen’s species ‘‘Lingula warthi.’’ Geol. Survey India Cat. No. 3/795. Specimen figured by Waagen [1885, Pl. LXXXYVI, figs. 9a-b] as Lingula (?) warthi. The same specimen is figured by Waagen [1891, Pl. II, figs. 17a-b] as Lingula (?) kiurensis, but from his description [1885, pp. 769-770] this is the form to which he intended to give the name warthi. I think it is the dorsal valve of Lingulella kiurensis. 5a. Copy of the figures given by Waagen [1891, Pl. II, figs. 17a-b] of the specimen represented by figure 5. The cardinal slopes are crushed in, which gives the depressed slopes described by Waagen [1885, p. 769]. The tront is also restored. 6. Type specimen of Lingula (?) kiurensis Waagen. Geol. Survey India Cat. No. 3/794. Specimen figured by Waagen [1885, p. 768, Pl. LX XXVI, figs. 8a-b] as Lingula (?) kiurensis. The same specimen is figured by Waagen [1891, Pl. II, figs. 18a-b] as Lingula (?) warthi, but from his description [1885, p. 768] this is the form to which he intended to give the name kiurensis. 6a. Copy of the figures given by Waagen [1891, Pl. II, figs. 18a—b] of the specimen represented in figure 6. The front of the shell is restored in Waagen’s figures, and the cardinal slopes widened out so as to make a diagrammatic figure. The specimens represented are both from Locality 357, Middle Cambrian limestones in the Neobolus beds of the Khussak group, near Kiura, Salt Range, India. , LINGULELLA wirtHt (Barrande) (p. 541). Ficure 7. Ventral valve from Locality 303c, passage beds between the Upper Cambrian and Ordovician near Hof, Bavaria. Enlarged one-third. Type specimen, copied from Barrande [1868a, fig. 63]. LINGULELLA CEDENS (Barrande) (p. 485). Ficure 8. Ventral valve from Locality 308¢, passage beds between the Upper Cambrian and Ordovician near Hof, Bavaria. Enlarged one-third. Type specimen, copied from Barrande [1868a, fig. 66]. 106 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XXX FRANCES WIESER DEL. HELIOTYPE CO S0STON PLATE XXX. 107 LINGULELLA ? (LINGULEPIS?) sQuaMosa (Holl) (p. 559). Fieure 9. Ventral valve from Locality 304g, Upper Cambrian Hollybush sandstones, Malvern Hills, England. Copied from Davidson’s figure [1866, Pl. II, fig. 7] of Lingula squamosa. LINGULELLA (LINGULEPIS?) prema (Salter) (p. 556). Figure 10. Ventral? valve from Locality 304f, Upper Cambrian ‘‘ Black shales,’’ Malvern Hills, England. Copied from Salter [1865, figs. 8a—b, p. 101). LINGULELLA SIGNATA (Barrande) (p. 532). Ficure 11. Dorsal? valve from Locality 303c, passage beds between the Upper Cambrian and Ordovician near Hof, Bavaria. Enlarged one-third. Copied from Barrande [1868a, fig. 73]. LINGULELLA? HUMILLIMA (Barrande) (p. 507). Figure 12. Dorsal valve from Locality 303c, passage beds between the Upper Cambrian and Ordovician near Hof, Bavaria. Enlarged one-third. Copied from Barrande [1868a, fig. 70]. LINGULELLA sp. undt. a Walcott (p. 541). Figure 13. Dorsal valve from Locality 310k, Upper Cambrian limestone on Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 51749a. LINGULELLA LINNARSSONI (Walcott) (p. 516). Fieure 14. Ventral valve, the type specimen, with the outer shell partly exfoliated. U.S.Nat. Mus. Cat. No. 35257a. 14a. Enlargement of the exterior surface on the anterior portion of a ventral valve. U.S. Nat. Mus. Cat. No. 35257b. The specimens represented are both from Locality 320n, Middle Cambrian limestone at Lovened, Djupadal, Province of Skaraborg, Sweden. LINGULELLA AGNOSTORUM (Wallerius) (p. 476). Ficure 15. Ventral valve greatly enlarged, and longitudinal outline of valve, from Locality 310i, passage beds between the Middle and Upper Cambrian, at Borgholm, Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 51747a. Oxso.us ? zoppr Walcott (p. 422). Ficure 16. Ventral valve, the type specimen, from Locality 354f, Middle Cambrian sandstone near Canal Grande, on the road to Punta Pintau, Sardinia, Italy. Copied from Bornemann [1891, Pl. XIX, fig. 17a]. 16a. Dorsal valve associated with the shell represented by figure 16. Copied from Bornemann [1891, Pl. XIX, fig. 16]. 16b. Side view of the shell represented in figure 16. Copied from Bornemann [1891, Pl. XIX, fig. 17b]. OBOLUs ? MENEGHINII Walcott (p. 403). Figure 17. A small exfoliated ventral valve, the type specimen, from Locality 354c, Middle Cambrian sandstone at Punta Pintau (Canal Grande), Sardinia. Copied from Bornemann’s figure [1891, Pl. XIX, fig. 14a] of Lingula petalon. 17a. A large ventral valve from Locality 354e, Middle Cambrian shale at Porto Canal Grande, Sardinia. Copied from Bornemann’s figure [1891, Pl. XIX, fig. 18] of Obolella sp. LINGULELLA BORNEMANNI (Walcott) (p. 483). Ficures 18, 18a, and 18b. More or less distorted and compressed ventral valves from Locality 354, Middle ? Cambrian, Canal Grande, Sardinia. Figures 18, 18a, and 18b are copied from Bornemann’s figures [1891, Pl. XIX, figs. 10a, 4, and 8, respectively] of Lingula attenuata. Figure 18 represents the type specimen. Fieure 18c. Dorsal ? valve from Locality 354, Middle ? Cambrian, Canal Grande, Sardinia. Copied from Bornemann’s figure [1891, Pl. XIX, fig. 7] of Lingula attenuata. 108 : PLATE XXX. OBOLUS SCHMALENSEEI (Walcott) (p. 412). Ficure 19. Broad form of the ventral valve, showing cast of pedicle furrow and a portion of the visceral cavity. U.S. Nat. Mus. Cat. No. 35291a. 19a. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 35291b. 19b. An elongate ventral valve. U.S. Nat. Mus. Cat. No. 35291c. 19c. Cast of a dorsal valve, showing the strongly marked area and margins of the posterior portion of the visceral cavity. U.S. Nat. Mus. Cat. No. 35291d. 19d. Partly exfoliated ventral and dorsal valves, the type specimen. U.S. Nat. Mus. Cat. No. 35291e. 19e. A small ventral valve. U.S. Nat. Mus. Cat. No. 35291f. The specimens represented are all from Locality 8w, Middle Cambrian limestone at Andrarum, Province of Christianstad, Sweden. ELKanta IDA (Billings) (p. 563). [ PI. LI, figs. 4, 4a-e.] Ficure 20. A probable ventral valve, from Locality 319, Lower Ordovician limestone of No. 1 of Billings’s section, Point Levis, Quebec, Canada. Geol. Survey Canada. 20a. Dorsal valve from the locality represented by figure 20. Geol. Survey Canada. BAI PLATE XXXI. a. Central lateral space of area. i. Transmedian muscle sear. a’. Outer lateral space of area. j. Anterior lateral muscle scar. ce. Trapezoidal area, including central, middle 1. Outside lateral muscle scar. lateral, and outside lateral muscle scars. p. Pedicle groove. f. Flexure line of area. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. LInGULELLA NatTHoRSTI Linnarsson (p. 521). Ficure 1. Cast of the interior of ventral valve, from Locality 320x, Lower Cambrian limestone at Andrarum, Province of Christianstad, Sweden. U.S. Nat. Mus. Cat. No. 18199a. la and 1b. Casts of the interior of dorsal valves associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. Nos. 18199b and 18199c, respectively. lc. Ventral valve preserving most of the shell, from Locality 8y, Lower Cambrian limestone at Skarésen, Dalarne, Sweden. U.S. Nat. Mus. Cat. No. 51739a. ; 1d and le. Dorsal valves associated with the ventral valve represented by figure lc. U.S. Nat. Mus. Cat. Nos. 51739b and 51739c, respectively. lf. Ventral valve associated with the ventral valve represented by figure 1c. U.S. Nat. Mus. Cat. No. 51739d. 1g and 1h. Dorsal valves associated with the ventral valve represented by figure lc. U.S. Nat. Mus. Cat. Nos. 51739e and 51739f, respectively. LINGULELLA SIEMIRADZEIE (Walcott) (p. 531). Ficure 2. Ventral valve, the type specimen, showing portion of the outer surface and the finely striated inner layer of shell. U.S. Nat. Mus. Cat. No. 35258a. : 2a. Cast of part of a dorsal valve. U.S. Nat. Mus. Cat. No. 35258b. The specimens represented are both from Locality 368, Middle Cambrian quartzitic sandstones in the Pepper Moun- tains, near Sandomierz, on the Vistula, Russian Poland. LINGULELLA FERRUGINEA Salter (p. 496). [Pl. XXIX, figs. 1, la-w, 2, 2a-f; Pl. XXX, fig. 1; and Pl. XXXV, figs. 4, 4a-b.] Figure 3. Ventral valve from Locality 310p, Middle Cambrian limestone at Borgholm, Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 51752a. 3a. Dorsal valve from Locality 310y, Middle Cambrian limestone of Kiviks Esperéd, Province of Malméhus, Sweden. U.S. Nat. Mus. Cat. No. 18205a. 5 3b. Short ventral valve from Locality 310z, Middle Cambrian limestone at Brantevik, Sweden, that is doubt- fully referred to this species. U.S. Nat. Mus. Cat. No. 51750a. 3c. Ventral valve doubtfully referred to the species from Locality 320m, Middle Cambrian at Kinnekulle, Province of Skaraborg, Sweden. Copied from Linnarsson’s figure [1876, Pl. IIT, fig. 28] of ‘‘Lingula or Lingulella sp.” LINGULELLA LEPIS (Salter) (p. 514). Freurr 4. Ventral valve from Locality 366k, Upper Cambrian shales, Penmorfa, Merionethshire, North Wales. Enlarged drawing of the specimen represented in figure 4a. Copied from Davidson [1871, Pl. XLIX, fig. 31a]. 4a. The ventral valve figured in figure 4, natural size. Copied from Davidson [1871, Pl. XLIX, fig. 31]. 4b. Cast of the interior of a ventral valve from Locality 8x, passage beds between the Upper Cambrian and the Ordovician, at Slemmestad, near Christiania, Norway, showing area, cast of pedicle groove, and visceral cavity. U.S. Nat. Mus. Cat. No. 51741a. de. Exterior of a strongly convex, highly polished ventral valve associated with the shell represented in figure 4b. Traces of radiating ribs, so strongly developed in figure 4d, are visible with a strong lens. U.S. Nat. Mus. Cat. No. 51741b. 4d. Dorsal valve associated with the shell represented in figure 4b, marked by strong radiating ribs and fine concentric strie. U.S. Nat. Mus. Cat. No. 51741c. de. Narrow form of dorsal valve, showing outline of elongate visceral cavity, from Locality 9f, Upper Cambrian limestones at Ncersnees, west of Christiania, Norway. U.S. Nat. Mus. Cat. No. 51742a. 4f. Cast of part of a broad form of a dorsal valve associated with the shell represented by figure 4b. U.S. Nat. Mus. Cat. No. 51741d. 110 PL. XXX\ MONOGRAPH LI GEOLOGICAL SURVEY UWS: FRANCES WIESER DEL. STON co. Bo MELIOTYPE AG PLATE XXXI. WLI LINGULELLA? PRIMEVA Hicks (p. 527). Ficures 5 and 5a. Ventral? valves from the Middle? Cambrian Caerfai group (see Locality 366c), south of St. Davids, South Wales. Copied from Davidson [1883, Pl. XVII, figs. 34 and 33, respectively]. Figure 5a represents the type specimen, Davidson’s figure being a copy of the one given by Hicks [187], Pl. XV, fig. 14]. LINGULELLA DAvist (McCoy) (p. 489). [Pl. XXX, figs. 2 and 2a.] Fieures 6 and 6a. Distorted ventral valves from ‘‘Lingula flags, Penmorfa, Tremadoc’”’ (see localities 366k and 3661), Merionethshire, North Wales. Copied from Davidson [1866, Pl. IV, figs. 10 and 11, respectively]. 6b. Distorted ventral valve from Locality 317b, Middle Cambrian, at Bellewstown, County Meath, Ireland. Copied from Davidson [1866, Pl. IV, fig. 12]. 6c. Enlargement of the area of a cast of a ventral valve from Locality 366a, Upper Cambrian shales, 6 miles east of Ffestiniog, Merionethshire, North Wales. U.S. Nat. Mus. Cat. No. 51740a. 6d. Cast of the interior of a distorted ventral valve associated with the specimen represented by figure 6c. U.S. Nat. Mus. Cat. No. 51740b. Specimen figured by Walcott [1898b, Pl. XX VII, fig. 2] as Obolus (Lingulella) davisti. 6e. Cast of the interior of a dorsal valve, showing the characteristic muscle scars of the genus. Locality 366n, Upper Cambrian shales at Portmadoc, Merionethshire, North Wales. U.S. Nat. Mus. Cat. No. 35239a. Specimen figured by Walcott [1898b, Pl. XX VII, fig. 4] as Obolus (Lingulella) davisii. 6f. Cast of the interior of a ventral valve associated with the shell represented in figure 6e, showing the out- lines of the visceral cavity and the vascular sinuses. U.S. Nat. Mus. Cat. No. 35239b.. Specimen figured by Walcott [1898b, Pl. XXVII, fig. 1] as Obolus (Lingulella) davisii. 6g. Cast of the interior of a ventral valve in which the characteristic punctate surface of the interior of the shell is shown by the large papillee scattered over the surface. Locality 366a, Upper Cambrian shales 6 miles east of Ffestiniog, Merionethshire, North Wales. U.S. Nat. Mus. Cat. No. 51740c. 6h. Cast of a distorted dorsal valve associated with the shell represented in figure 6g, preserving the impressions of the transmedian and outside Jateral muscle scars. U.S. Nat. Mus. Cat. No. 51740d. Specimen figured by Walcott [1898b, Pl. X XVII, fig. 5] as Obolus (Lingulella) davisii. lee) OOO 62667°—vo1 51, pr 2—12 8 PLATE XXXII. h. Central muscle scar. j. Anterior lateral muscle scar. LINGULELLA DAVIDSONI (Barrande) (p. 489). Fiaure 1. Partly exfoliated ventral valve, the type specimen, showing lamellated shell, from Locality 303m, Ordovician, Etage d4, at Lieben, Bohemia. Enlarged one-third. Copied from Barrande [1879b, Pl. CIV, fig. vur:1A]. la. Side view of the specimen represented by figure 1. Copied from Barrande [1879b, Pl. CIV, fig. virr:1b]. lb. Less elongate ventral valve than that represented by figure 1, from Locality 303n, Ordovician, Etage d4, at Wraz, Bohemia. Enlarged one-third. Copied from Barrande [1879b, Pl. CIV, fig. vmr:3A]. lc. Side view of the specimen represented by figure 1b. Copied from Barrande [1879b, Pl. CIV, fig. vur:3b]. 1d. Enlargement of the area and posterior portion of figure le. Copied from Barrande [1879b, Pl. CIV, fig. vur:4E]. le. Interior of a ventral valve from Locality 3030, Ordovician, Etage d4, at Lodenitz, Bohemia. Copied from Barrande [1879b, Pl. CIV, fig. vi1:4]. LINGULELLA? rnsons (Barrande) (p. 508). Fieure 2. Interior of ventral valve from Locality 303d, Lower Ordovician, Etage dl, at Swarow, Bohemia. Copied from Barrande [1879b, Pl. CV, fig. x:4A]. 2a. Partly exfoliated dorsal valve from same bed as specimen represented by figure 2. Copied from Bar- rande [1879b, Pl. CV, fig. x:3A]. 2b and 2c. Interior of ventral valves, showing area, from Locality 303e, Lower Ordovician, Etage dl, at Sta. Benigna, Bohemia. Copied from Barrande [1879b, Pl. CV, figs. x:5A and x:6A, respectively]. Figure 2c represents the type specimen. 2d. Enlargement of the area of figure 2c. Copied from Barrande [1879b, Pl. CV, fig. x:6E]. 2e. Enlargement of surface of shell and impression of interior surface from the anterior portion of the valve. Locality 303d, Lower Ordovician, Etage dl, at Swarow, Bohemia. Copied from Barrande [1879b, Pl. CV, fig. x:1f]: Lineuia? exrmra Barrande (p. 301). V'icureE 3. Fragment of the shell greatly enlarged to show complex character of the surface ornamentation. Inserted for comparison. Locality 3031, Lower Ordovician, Etage d1, at Libetschov, Bohemia. Copied from Barrande [1879b, Pl. CV, fig. r:f]. LINGULELLA? SIMPLEX (Barrande) (p. 534). Tiaure 4. Ventral valve showing portion of area where the thin shell has been pressed down into it. Locality 303p, Lower Ordovician, Etage d3, near Beraun, Bohemia. Copied from Barrande [1879b, Pl. CIV, fig. vi:lA]. 4a. Dorsal valve from Locality 303a, Lower Ordovician, Etage d3, at Trubin, Bohemia. Copied from Bar- rande [1879b, Pl. CIV, fig. vr:4A]. ‘ 4b. Side view of specimen represented by figure 4a. Copied from Barrande [1879b, Pl. CIV, fig. vr:4B]. OBoLus (PALHOBOLUS) BRETONENSIS (Matthew) (p. 426). Fiaure 5. Cast of the interior of a flattened ventral valve, the type specimen, slightly compressed laterally. University of Toronto, Canada. Reproduced froma photograph of one of Matthew’s specimens; it may be the one used by him in drawing figure 2b of his paper [1903, Pl. IX], but closer identification is impossible. 5a. Cast of part of the interior of a ventral valve. University of Toronto, Canada. 5b. Exterior ofa nearly entire dorsal valve. University of Toronto, Canada. Reproduced from a photograph of one of Matthew’s specimens; it may be the one used by him in drawing figure 2d of his paper [1903, Pl. LX]. 5e. Exterior of a dorsal valve, showing finely preserved outer surface. University of Toronto, Canada. Repro- duced from a photograph of one of Matthew’s specimens; it may be the one used by him in drawing figure 2a of his paper [1903, Pl. IX]. 5d. Cast of part of a broken dorsal valve in which the area is preserved. University of Toronto, Canada. 5e. Enlargement of a cast of the interior of a dorsal valve. University of Toronto, Canada. Reproduced from a photograph of one of Matthew’s specimens; it may be the one used by him in drawing figure 2e of his paper [1903, Pl. LX]. The exact locality represented by the specimens figured is not known. It is probable, however, that they were all collected at the type locality (344b), Middle Cambrian shales of Division E3d of Matthew’s Etcheminian, Dugald Brook, Cape Breton, Nova Scotia. Fiaures 5f and 5g. Exterior of nearly perfect ventral and dorsal valves, from Locality 10p, Middle Cambrian sand- stones of Division E2b of Matthew on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. : Cat. Nos. 51664a and 51664b, respectively. 114 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL, XXXII FRANCES WIESER DEL. HELIOTYPE CO. BOSTON Job IND) SOOILD: 115 = PLATE XXXIII. LINGULELLA LENS (Matthew) (p. 512). Ficure 1, Ventral valve broken and embedded in limestone. University of Toronto, Canada. Type specimen, figured by Matthew [1901, Pl. V, fig. 8a] as Lingula ? lens. Ja. Ventral valve showing outline of a smaller shell than that represented by figure 1. U.S. Nat. Mus. Cat. No. 51767a. lb, 1c, and 1d. Partly exfoliated dorsal valves varying somewhat in outline and size. U.S. Nat. Mus. Cat. Nos. 51767b, 51767c, and 51767d, respectively. The specimens represented are all from Locality 10r, Upper Cambrian shales of Division C3a? of Matthew, at McAdam Shore, East Bay, Cape Breton, Nova Scotia. LINGULELLA CONCINNA Matthew (p. 486). (Pl. XXXIV, figs. 1, la-r.] Ficure 2. Ventral valve broadened by movement in the fine shale of Locality 3h, Upper Cambrian, McNeil Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51762s. 2a. Ventral valve that occurs on the same hand specimen with the shell represented by figure 2. It has been elongated by the movement which broadened figure 2. U.S. Nat. Mus. Cat. No. 51762t. 2b, Ventral valve associated with the shell represented by figure 2, preserving its original outline. U.S. Nat. Mus. Cat. No. 51762u. (See note following description of fig. 2h.) 2¢e. Small dorsal valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 51762v. 2d. Dorsal valve, the type specimen, slightly broadened by compression; from Locality 307, Upper Cam- brian, McLeod Brook, Cape Breton, Nova Scotia. University of Toronto, Canada. Drawn from one of the specimens figured by Matthew [1901, Pl. V, figs. 2a—b], but closer identification is impossible. 2e. Dorsal valve associated with the specimen represented by figure 2, slightly broadened by compression. U.S. Nat. Mus. Cat. No. 51762w. 2f. Dorsal valve associated with the specimen represented by figure 2, more or less distorted by compression in the shale. U.S. Nat. Mus. Cat. No. 51762x. . Distorted dorsal valve from Locality 372, Upper Cambrian shale at Upper Leitches Creek, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52449a. 2h. Dorsal valve associated with the ventral valve represented by figures 2 and 2b. U.S. Nat. Mus. Cat. No. 51762y. Figures 2b and 2h preserve the original convexity and outline of the shell more perfectly than those compressed in the fine shales. Osoius (WesronrA) ELLA (Hall and Whitfield) (p. 455). (Pl. XLVII, figs. 1, la-p.] Fictres 3 and 3a. Associated dorsal valves distorted by movement in shale, one being broadened, and the other elongated. U.S. Nat. Mus. Cat. Nos. 51684a and 51684b, respectively. 3b and 3c. Dorsal and ventral valves compressed and distorted in fine shale. U.S. Nat. Mus. Cat. Nos. 51684c and 51684d, respectively. The figures all represent specimens from Locality 8c, Middle Cambrian shales near Ophir, Utah, and are intro- duced to illustrate the forms this species may often take where the fine shells have been more or less compressed and stretched. They should be compared with the prevailing form of the species as shown on Plate XLVII. LINGULELLA (LINGULEPIS) EXIGUA (Matthew) (p. 551). [Pl. XLIII, figs. 1, la-z.] Fiaure 4, Group of young shells occurring in fine, arenaceous shale, Locality 3i, Middle Cambrian on McLean Brook, 1.5 miles west of Marion Bridge, Cape Breton, Nova Scotia, in which the adult specimens represented on Plate XLIII occur. U.S. Nat. Mus. Cat. No. 34761s. 4a. Specimen in which the substance of the shell has been etched by acid so as to leave in relief the siliceous matter filling the fractures in the shell. Locality 10s, Middle Cambrian sandstone on McLean Brook, near Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52468a. The original specimen is 12 mm. in length. The system of fractures is very complicated within the two main lines of fracture which cross each other obliquely, forming rhomboidal spaces. 116 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XXxXIII i Ses ee) er Res > > to FRANCES WIESER DEL. HELIOTYPE CO, BOSTON ¢ PROPERTY OF te THE iG yah e@z ior’ CUE GAR NEGF LIBRAR Jee ID) 2OXOCIUWE, 117 PLATE XXXIV. LINGULELLA CONCINNA Matthew (p. 486). [Pl. XX XIU, figs. 2, 2a-h] Fiaure 1. This ventral valve is somewhat doubtfully referred to this species. The specimen from which the figure was drawn occurs in Locality 310h, Upper? Cambrian shales in the Province of Skane, Sweden, and is more nearly related to some forms of Lingulella concinna than to other species from the Upper Cambrian and Lower Ordovician. U.S. Nat. Mus. Cat. No. 14932a. Ja-h. Ventral valves illustrating variations in outline, convexity, etc., from Locality 3h, Upper Cambrian shale on McNeil Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. Nos. 51762a-h, respectively. li-q. Dorsal valves associated with the ventral valves represented by figures la-h. U.S. Nat. Mus. Cat. Nos. 517621-q, respectively. lr. Three ventral valves and fragments of a dorsal valve associated with the shells represented by figures la-q (X 2). U.S. Nat. Mus. Cat. No. 51762r. OBOLUS SEPTALIS (Walcott) (p. 414). [Pl. XXIM, fig. 34] Figure 2. Exterior of dorsal valve. Collection of Mr. Byron E. Walker, Toronto, Canada. 2a. Cast of interior of dorsal valve, the type specimen. U.S. Nat. Mus. Cat. No. 51612a. The specimens are both from Locality 14s, Middle Cambrian Ogygopsis zone on Mount Stephen, British Columbia. LINGULELLA (LINGULEPIS) ACUMINATA (Conrad) (p. 545). [Pl. XL, figs. 1, 1a-s; Pl. XL, figs. 1, la-n; and Pl. XLII, figs. 1, 1a-o.] Fiaure 3. Ventral valve with the apex worn off, from Locality 7z, Upper Cambrian limestone about 3 miles southeast of Emigrant Pass, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 51884a. 3a. Ventral valve intermediate in form between specimens represented by figures 3 and 3b, from Locality 7y, Upper Cambrian limestones 2.5 miles southeast of Emigrant Pass, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 56967a. 3b. Broad form of ventral valve with apex broken off, from Locality 7x, Upper Cambrian limestones 2.5 miles southeast of Emigrant Pass, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 56967b. 3c and 3d. Dorsal valves associated with the shell represented by figure 3. U.S. Nat. Mus. Cat. Nos. 51884b and 51884c, respectively. 3e. A small, slender ventral valve associated with the shell represented by figure 3. U.S. Nat. Mus. Cat. No. 51884d. 118 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XXXIV FRANCES WIESER DEL, HELIOTYPE CO BOSTON EN 2OOCy. 119 PLATE XXXY. a. Central lateral space of area. p. Pedicle groove. a’. Outer lateral space of area. s. Median septum. f. Flexure line of area. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. j. Anterior lateral muscle scar. LINGULELLA cCOoLLictA (Matthew) (p. 486). Figure 1. Exterior of an imperfect ventral valve, the type specimen. University of Toronto, Canada. la. Partly exfoliated ventral valve, showing visceral area and vascular sinuses. University of Toronto, Canada. : 1b. Crushed and broken cast of the interior of a ventral valve. University of Toronto, Canada. The specimens represented by figures 1, la—b are from Locality 138n’, Middle Cambrian sandy shales of Division E3e, Dugald Brook, Cape Breton, Nova Scotia. The figures are drawn from three of the specimens illustrated by Mat- thew [1899b, Pl. I, figs. 3a-e], but closer identification is impossible. Figure lc. Exterior of a dorsal valve broadened and distorted by compression. Locality 13m, Middle Cambrian sandstones of Division E3f, Gillis Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51772a. 1d. Imperfect cast of interior of a dorsal valve from Locality 13n’, Middle Cambrian sandy shales of Division E3e, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52453a, le. Imperfect cast of interior of a flattened dorsal valve from Locality 10p, Middle Cambrian sandy shales of Division E2b, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 35294a. 1f. Cast of the interior of a ventral valve associated with the shell represented in figure le. U.S. Nat. Mus. Cat. No. 35294b. 2. Cast of interior of ventral valve from Locality 18m, Middle Cambrian sandstones of Division E3f, Gillis Brook, Cape Breton, Nova Scotia, showing area and position of vascular sinuses. U.S. Nat. Mus. Cat. No. 57084a. i ; 2a. Exterior of a slightly distorted ventral valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 57084b. 2b. Broad ventral valve, doubtfully referred to this species, from Locality 10p, Middle Cambrian sandy shales. of Division E2b, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 57083a. 2c. Dorsal valve associated with the specimen represented by figure 2a. U.S. Nat. Mus. Cat. No. 57084c. 2d. Interior of a dorsal valve associated with the specimen represented by figure 2a, showing a strong median ridge and the position of the central muscle scars. U.S. Nat. Mus. Cat. No. 57084d. Figures 2, 2a-d represent forms corresponding to those referred by Matthew [1903, pp. 114-115] to Leptobolus collicia collis. LINGULELLA CANIA (Walcott) (p. 484). Ficures 3 and 3b. Casts of the interior of ventral valves from Locality 3i, Middle Cambrian sandy shale on McLean Brook, 1.5 miles west of Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. Nos. 5245la and 52451c, respectively. Figure 3 represents the type specimen. 3a. Partly exfoliated ventral valve associated with the shells represented in figures 3 and 3b. U.S. Nat. Mus. Cat. No. 52451b. 3c. Exterior of dorsal valve from Locality 10s, Middle Cambrian sandstone on McLean Brook, near Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 35295a. 3d. Cast of interior of dorsal valve associated with the specimens represented by figures 3 and 3b. U.S. Nat. Mus. Cat. No. 52451d. LINGULELLA FERRUGINEA Salter (p. 496). [Pl]. XXIX, figs. 1, la-w, 2, 2a-f; Pl. XXX, fig. 1; and Pl. XX XT, figs. 3, 3a-c.] Ficures 4 and 4a. Partly exfoliated ventral valves, showing cast of the area and pedicle furrow, from Locality 3h, Middle Cambrian arenaceous shales, McNeil Brook, 1.5 miles east of Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. Nos. 51758a and 51758b, respectively. 4b. Dorsal valve associated with the ventral valves represented by figures 4 and 4a. U.S. Nat. Mus. Cat. No. 51758c. 120 yo . GEOLOGICAL SURVEY U. FRANCES WIESER DEL. HELIOTYPE CO BCS U9 hi ual r PLATE XXXyV. IPA LINGULELLA ATAVA (Matthew) (p. 479). Fiaure 5. Exterior of ventral valve from Locality 18n’, Middle Cambrian sandstones of Division E3e, Dugald Brook, Cape Breton, Nova Scotia. Type specimen, figured by Matthew [1899b, Pl. II, fig. la] as Leptobolus atavus. 5a and 5b. Partly exfoliated ventral valves, showing area, pedicle furrow, and outline of visceral cavity. Locality 10p, Middle Cambrian sandstones of Division E2b, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. Nos. 35293a and 35293b, respectively. 5c. Dorsal valve associated with the specimens represented by figure 5. University of Toronto, Canada. Specimen figured by Matthew [1899b, PI. II, fig. 1d] as Leptobolus atavus. 5d. Cast of interior of dorsal valve, showing outline of visceral area, position of anterolateral muscle scars, vascular sinuses, and area. Locality 13n’, Middle Cambrian sandy shales of Division E3e, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52450a. 5e. Dorsal valve. The specimen can not now be located. It was in the collections of the United States National Museum, but the locality is unknown. 5f, 5g, and 5h. Casts of laterally compressed dorsal valves associated with the ventral valves represented by figures 5a and 5b. U.S. Nat. Mus. Cat. Nos. 35293c, 35293d, and 35293e, respectively. LINGULELLA FLUMENIS (Matthew) (p. 500). Fieure 6. Exterior of imperfect ventral valve. University of Toronto, Canada. [1903, Pl. XI, fig. 7a] as Leptobolus flumenis. 6a. Interior of dorsal valve. University of Toronto, Canada. Specimen figured by Matthew [1903, Pl. XI, fig. 7b] as Leptobolus flumenis. 6b. Cast of interior of dorsal valve. University of Toronto, Canada. Pl. XI, fig. 7e] as Leptobolus flumenis. Type specimen, figured by Matthew Specimen figured by Matthew [1903, The specimens represented are all from Locality 325a, Middle Cambrian shales of Division C2c on McNeil Brook, Cape Breton, Nova Scotia. LINGULELLA TORRENTIS (Matthew) (p. 535). Figure 7. Ventral valve from Locality 344f, Middle Cambrian shales of Matthew’s Coldbrook group, Dugald Brook, Cape Breton, Nova Scotia. University of Toronto, Canada. Type specimen, figured by Matthew [1903, Pl. VI, fig. 1] as Leptobolus torrentis. LINGULELLA ATAVA INSULZ (Matthew) (p. 480). Fieures 8 and 8a. Ventral and dorsal valves from Locality 307d, Middle Cambrian sandy limestone ot Division E2a?, at Youngs Point near George River Station, Cape Breton, Nova Scotia. University of Toronto, Canada. Specimens figured by Matthew [1903, Pl. VI, figs. 4a and 4b] as Leptobolus atavus insule. Figure 8 represents the type specimen. LINGULELLA oRA (Walcott) (p. 522). Figure 9. Exterior of a broken ventral valve, the type specimen, from Locality 9p, Upper Cambrian limestone, 15 , miles northwest of Fort Sill, Comanche County, Oklahoma. U.S. Nat. Mus. Cat. No. 51794a. 9a and 9a’. Top and side views of a partly exfoliated ventral valve which illustrates the thickness of the shell, from Locality 9q, Upper Cambrian limestone, 15 miles northwest of Fort Sill, Comanche County, Oklahoma. U.S. Nat. Mus. Cat. No. 51795a. 9b and 9b’. Top and side views of a ventral valve associated with the shell represented in figure 9, showing the outer surface of one of the inner layers of the shell. U.S. Nat. Mus. Cat. No. 51794b. 9c and 9c’. Top and side views of an elongate dorsal valve associated with the shell represented in figure $. U.S. Nat. Mus. Cat. No. 51794c. é 9d. Short broad form of dorsal valve associated with the shell represented in figure 9. U.S. Nat. Mus. Cat. No. 51794d. OE Ng fy Stes Oe Ue iat Br accra Te Ea ep hoe i Pay y, ' ie Wil a em Pan ig a sean eave SP i, Wa LDU Yahinn aa a PLATE XXXVI. c. Trapezoidal area, including central, middle p. Pedicle groove. lateral, and outside lateral muscle scars. s. Median septum. g. Umbonal muscle scar. v. Visceral cavity. h. Central muscle sear. ; vs. Main vascular sinus. i. Transmedian muscle scar. ivs. Lateral branches of vascular system. j. Anterior lateral muscle scar. pvs. Peripheral branches of vascular system. k. Middle lateral muscle scar. x. Heart-shaped cavity. 1. Outside lateral muscle scar. OBOLUS SELWYNI (Matthew) (p. 413). (Pl. XX XVII, figs. 1, 1a-f.] Figure 1. Interior of a dorsal valve, showing a portion of the visceral area and adjoining parts; also the striation of one of the inner layers of the shell. University of Toronto, Canada. Redrawn (with fig. 1c) from the specimens on which Matthew [1903] based the diagrammatic figures in the left-hand figure on page 117 and figures la and Ic of Plate VII of his paper. Ja. Exfoliated ventral valve, showing the visceral area and adjoining portions of the interior of the shell. University of Toronto, Canada. ° 1b. Side outline of specimen represented by figure la. lc. Interior of a ventral valve, longitudinally compressed, which emphasizes the main vascular sinuses and, the lateral branches of the vascular system. University of Toronto, Canada. Redrawn (with fig. 1) from the specimens on which Matthew [1903] based the diagrammatic figures in the left-hand figure on page 117 and figures la and lc of Plate VII of his paper. ld. Interior of a dorsal valve, showing portions of the vascular system. University of Toronto, Canada. le, 1f, and lg. Interior of dorsal valves, showing variation in position of the central and anterior lateral muscle scars. University of Toronto, Canada. lh. Dorsal valve longitudinally compressed, giving it a very broad form. This may be compared with figures le and lf of Plate XX XVII. University of Toronto, Canada. 2. Cast of interior of a ventral valve, broadened by compression. University of Toronto, Canada. Specimen figured by Matthew [1902c, Pl. I, fig. 4b] as Obolus xquiputeis. 2a. Cast of interior of a dorsal valve. University of Toronto, Canada. Specimen figured by Matthew [1902c, Pl. I, fig. 4d] as Obolus xquiputeis. 2b. Cast of the interior of a dorsal valve. University of Toronto, Canada. The specimens represented are all from Locality 307d, Middle Cambrian sandy limestone of Division E2a? on Youngs Point, near George River Station, Cape Breton, Nova Scotia. LINGULELLA uPiIs (Walcott) (p. 538). Ficures 3.and 3’. Top and side views of partly exfoliated ventral valve, the type specimen, from Locality 14i, Upper Cambrian limestone 1 mile west of Cherokee, San Saba County, Texas. U.S. Nat. Mus. Cat. No. 51804a. 3a. Fragmentary dorsal valve associated with the ventral valve represented by figure 3. U.S. Nat. Mus. Cat. No. 51804b. LINGULELLA BELLA (Walcott) (p. 481). [Pl. XIX, figs. 2, 2a-q.] Ficure 4. Slab of arenaceous shale with numerous well-preserved shells from Locality 114b, Lower Ordovician sand- stone 1 mile north of Lance Cove, Great Belle Island, Conception Bay, Newfoundland. U. $. Nat. Mus. Cat. No. 27308n. 124 U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. HELIOTYFE co BOSTON MONOGRAPH LI PL. XXX ns - PLATE exec sill . PLATE XXXVII. ce. Trapezoidal area, including central, p. Pedicle groove. middle lateral, and outside lateral * ps. Parietal band. muscle scars. s. Median septum. g. Umbonal muscle sear. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. i. Transmedian muscle scar. ivs. Lateral branches of the vascular system. j. Anterior lateral muscle scar. x. Heart-shaped cavity. 1. Outside lateral muscle scar. OBOLUS SELWYNI (Matthew) (p. 413). [PI]. XXXVI, figs. 1, la-h, 2, 2a-b.] Ficure 1. Exterior of a distorted ventral valve. University of Toronto, Canada. Possibly one of the specimens used by Matthew in preparing the diagrammatic figures mentioned under figure 1c. la. Cast of an interior ofa ventral valve. University of Toronto, Canada. 1b. Cast of an interior of a ventral valve that has been compressed laterally. University of Toronto, Canada. Possibly one of the specimens used by Matthew in preparing the diagrammatic figures mentioned under figure 1c. le. Cast of an interior of a dorsal valve. University of Toronto, Canada. Redrawn from the specimen upon which Matthew [1903] based the diagrammatic figures in the right-hand figure on page 117 and in figure 1b of Plate VII of his paper. It may be taken as the type. ld. Finely preserved interior of a ventral valve. University of Toronto, Canada. Possibly one of the speci- mens used by Matthew in preparing th e diagrammatic figures mentioned under figure Ic. le. Interior of the posterior portion of a dorsal valve. University of Toronto, Canada. 1f. Cast of an interior of a dorsal valve. University of Toronto, Canada. Possibly one of the specimens used by Matthew in preparing the diagrammatic figures mentioned under figure lc. The specimens represented are all from Locality 307d, Middle Cambrian sandy limestone of Division E2a? on Youngs Point, near George River Station, Cape Breton, Nova Scotia. LINGULELLA (LINGULEPIS) sTaRRI (Matthew) (p. 559). Ficure 2. Poorly preserved ventral valve. University of Toronto, Canada. 2a. Dorsal valve preserving a portion of the shell. University of Toronto, Canada. 2b. Cast of a portion of the interior of a ventral valve. University of Toronto, Canada. The specimens represented are all from Locality 308ce, Upper Cambrian shales of Matthew’s Johannian at St. John, New Brunswick. According to Matthew the type specimens have been either mislaid or lost. All the figures are drawn from new material collected by him at the type locality. LINGULELLA MINOR (Matthew) (p. 519). Ficure 3. Cast of the exterior of a ventral valve slightly compressed and distorted in the shale. University of Toronto, Canada. Type specimen, figured by Matthew [1892, Pl. XII, fig. 5a] as Lingulella starri minor. 3a. Dorsal valve from which nearly all of the shell is exfoliated. University of Toronto, Canada. Specimen figured by Matthew [1892, Pl. XII, fig. 5b] as Lingulella starri minor. 8b. Enlargement of the outer surface of the shell. University of Toronto, Canada. 3c. Ventral valve from siliceous shale. U.S. Nat. Mus. Cat. No. 51765a. 3d and 3e. Small ventral and dorsal valves from a fine arenaceous shale. U.S. Nat. Mus. Cat. Nos. 51765b and 51765c, respectively. 3f and 3g. Small broad form of ventral and dorsal valves associated with narrower forms represented by figures 3d and 3e. U.S. Nat. Mus. Cat. Nos. 51765d and 51765e, respectively. The specimens are all from Locality 2x, Upper Cambrian sandstones on Long Island, Kennebecasis Bay, St. John County, New Brunswick. 126 XVI PL. XX MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL HELIOTYPE CO. BOSTON iy PLATE XXXVII. D7 LINGULELLA ROTUNDA (Matthew) (p. 530. Ficure 3h. Exterior of a small ventral valve. U.S. Nat. Mus. Cat. No. 51770a. 3i. Cast of interior of ventral valve. U.S. Nat. Mus. Cat. No. 51770b. 3j and 3k. Casts of interior of dorsal valves. U.S. Nat. Mus. Cat. Nos. 51770c¢ and 51770d. The specimens represented are all from Locality 3i, Middle Cambrian sandy shale on McLean Brook, 1.5 miles west of Marion Bridge, Cape Breton, Nova Scotia. LINGULELLA (LINGULEPIS) ROBERTI (Matthew) (p. 557). Ficure 4. Ventral valve preserving a portion of the outer surface. University of Toronto, Canada. 4a. Cast of the interior of a ventral valve, the type specimen. University of Toronto, Canada. (See note following 4d.) 4b. Cast of the interior of a dorsal valve, preserving outline and convexity of valve and impressions of muscle scars. University of Toronto, Canada. (See note following 4d.) 4c. Enlargement of a portion of the outer surface of the anterior portion of a dorsal valve. University of Toronto, Canada. 4d. Dorsal valve distorted by compression. University of Toronto, Canada. The figures are all drawn from specimens in Matthew’s type material. It is possible that the specimens represented by figures 4a and 4b are the ones figured by Matthew [1895b, PI. I, figs. 2a and 2b, respectively], but closer identification is impossible. The specimens represented are all from Locality 307d, Middle Cambrian sandy limestone of Division E2a? at Youngs Point, near George River Station, Cape Breton, Nova Scotia. paihaae sat! AARON Ne aa wi ney ed Ves. Snueeen > yet ft, 4 a i Yin » P : ‘ aa i i 62667°—vox 51, pr 2129 tae 7 ab 1 PLATE XXXVIIT. a. Central Jateral space of area. s. Median septum. a’. Outer lateral space of area. v. Visceral cavity. f. Flexure line of area. vs. Main vascular sinus. h. Central muscle scar. ivs. Lateral branches of the vascular system. j. Transmedian muscle scar. pvs. Peripheral branches of the vascular system. p. Pedicle groove. x. Heart-shaped cavity. LINGULELLA MARTINENSIS Matthew (p. 518). Figure 1. Exterior of an unusually well-preserved ventral valve. University of Toronto, Canada. Drawn from a specimen in Matthew’s type and figured material, but closer identification is impossible. Ja. Cast of the interior of a ventral valve. University of Toronto, Canada. Type specimen figured by Matthew [1895a, Pl. II, fig. 6d]. ; lb. Interior of a ventral valve from which nearly all of the inner layers of the shell have been exfoliated. University of Toronto, Canada. Drawn from aspecimen in Matthew’s type and figured material, but closer identification is impossible. le. Interior of a dorsal valve. University of Toronto, Canada. Drawn from aspecimen in Matthew’s type and figured material, but closer identification is impossible. 1d. Cast of the interior of a dorsal valve. University of Toronto, Canada. Specimen figured by Matthew [1895a, Pl. IT, fig. 6b]. le. Enlargement of the area of the specimen represented by figure id. The specimens represented by figures 1, la—e are from Locality 2f, Middle Cambrian sandstones of Division 1b1, on Hanford Brook, St. John County, New Brunswick. Fieures lf and lg. Ventral and dorsal valves which occur in the collection of the University of Toronto, Canada, labeled by Matthew as Lingulella dawsoni from Division lc of the St. John slate. They appear to be’ more nearly related to Lingulella martinensis. They may or may not be the specimens illustrated by Matthew [1886, Pl. V, figs. 9, 9a-c]. LINGULELLA GRANDIS (Matthew) (p. 502). Fieure 2. Partly exfoliated dorsal valve. University of Toronto, Canada. 2a. Cast of the interior of the posterior portion of a ventral valve. University of Toronto, Canada. Figures 2 and 2a (with 2c and 2d) are drawn from specimens in Matthew’s type material of Lingulella ? cuneata, but it is impossible to tell which of these he figured [1894, Pl. XVI, figs. 5a—b]. Figure 2b. Slightly imperfect cast showing the greater part of the interior of a ventral valve. University of Toronto, Canada. Type specimen, figured by Matthew [1894, Pl. XVI, fig. 7a] as Leptobolus grandis. 2c. Cast of the interior of a ventral valve. University of Toronto, Canada. 2d. Cast of the interior of a dorsal valve. University of Toronto, Canada. Figures 2c and 2d (with 2 and 2a) are drawn from specimens in Matthew’s type material of Lingulella ? cuneata, but it is impossible to tell which of these he figured [1894, Pl. XVI, figs. 5a—b]. : Fieure 2e. Posterior portion of a dorsal valve, showing cast of the area. University of Toronto, Canada. Labeled by Matthew as Leptobolus grandis. i 2f. Part of the interior of a dorsal valve. University of Toronto, Canada. Specimen figured by Matthew [1894, Pl. XVI, fig. 7b] as Leptobolus grandis. The specimens represented by figures 2, 2a-f are all from Locality 301s, Lower Ordovician sandstone at McAphee’s Corner, Hardingville, St. John County, New Brunswick. Oxsotts BELLI (Billings) (p. 386). Figures 3 and 3a. Ventral valves from Locality 319n, Ordovician, on the island of Montreal, Canada. Geol. Survey Canada. Redrawn from the specimens figured by Billings [1859, pp. 431-482, figs. 7 and 8], but closer identification is impossible. Figure 3 may be taken as the type. 3b. Dorsal valve associated with the specimens represented by figures 3 and 3a. Geol. Survey Canada. LINGULELLA WELLERI (Walcott) (p. 539). Figure 4. Compressed and somewhat crushed ventral valve, the type specimen, showing only the general outline and the outer surface. U.S. Nat. Mus. Cat. No. 35292a. 4a. Apex and posterior portion of the ventral valve, preserving the convexity. U.S. Nat. Mus. Cat. No. 35292b. 4b. A compressed dorsal valve. U.S. Nat. Mus. Cat. No. 35292c. The specimens represented are all from Locality 11e, Upper Cambrian sandstone, O’ Donnell and McManniman’s quarry, Newton, New Jersey. "130 e U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XXXVIil FRANCES WIESER DEL. HELIOTYPE CO., BOSTON. i Tne Neale bly : | PALIT SOC PLATE XXXIX. a. Central lateral space of area. 1. Outside lateral and middle lateral muscle a’. Outer lateral space of area. sears on dorsal valve. f. Flexure line of area. p. Pedicle groove. h. Central muscle sear. s. Median septum. i. Transmedian muscle scar. y. Visceral cavity. j. Anterior lateral muscle sear. vs. Main vascular sinus. LINGULELLA WANNIECEI Redlich (p. 538). Ficure 1. Elongate form of the ventral valve. U.S. Nat. Mus. Cat. No. 517440. ja, 1b, and 1c. Short, broad, subtriangular forms of the ventral valve. U.S. Nat. Mus. Cat. Nos. 51744a, 51744b, and 51744c, respectively. 1d. Cast of the interior of a ventral valve, showing the area, visceral area, and vascular sinuses. U.S. Nat. Mus. Cat. No. 51744d. le. Imperfect interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51744e. : 1f. Dorsal valve in position against the ventral valve, showing the area of the ventral valve. U.S. Nat. Mus. Cat. No. 517441. 1g, lh, and li. Exteriors of dorsal valves, varying somewhat in outline. U.S. Nat. Mus. Cat. Nos. 51744g, 51744h, and 517441, respectively. 1j and 1k.- Interiors of imperfect dorsal.valves. U.S. Nat. Mus. Cat. Nos. 51744j and 51744k, respectively. 11. Interior of a remarkably well preserved dorsal valve. U.S. Nat. Mus. Cat. No. 517441. Im. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51744m. In. Interior of a dorsal valve, showing anterior lateral scars and narrow ridges in the position of the main vascular sinuses. U.S. Nat. Mus. Cat. No. 51744n. . "The specimens represented are all from Locality 15r, Middle Cambrian argillaceous shale at Khussak, Salt Range, India. LINGULetya Fucus! Redlich (p. 502). Figure 2. Narrow elongate form which may be compared with figure 3. U.S. Nat. Mus. Cat. No. 51746a. 2a. Cast of a very small dorsal valve. U.S. Nat. Mus. Cat. No. 51746b. 2b and 2c. Dorsal valves referred to this species. U.S. Nat. Mus. Cat. Nos. 51746c and 51746d, respectively. 3. Ventral valve, the type specimen. Copied from Redlich [1899, Pl. I, fig. 10c]. The specimens represented are all from Locality 15r, Middle Cambrian argillaceous shale at Khussak, Salt Range, India. ’ LINGULELLA IssE (Walcott) (p. 509). [Text figs. 43A-F, p. 510.] Fieures 4and 4a. Narrow and broad forms of ventral valves, with exterior shell partly exfoliated. U.S. Nat. Mus. Cat. Nos. 51808a and 51808b, respectively. Figure 4a represents the type specimen. 4a’. Side outline of specimen represented by figure 4a. 4b and 4b’. Exfoliated dorsal valve and side outline. U.S. Nat. Mus. Cat. No. 51808c. The specimens represented are all from Locality 15d, Upper Cambrian limestone near Cave Spring, Fish Spring Range, Utah. ; OBOLUS MCCONNELLI PELIAS (Walcott) (p. 398). [Pl. XXII, figs. 3b-c.] Figure 5. Ventral valve with outer layer of shell exfoliated, from Locality 15p, Middle Cambrian limestones near the north end of the Fish Spring Range, Utah. U.S. Nat. Mus. Cat. No. 51597a. da and 5b. Partly exfoliated dorsal valves associated with the specimen represented by figure 5. U.S. Nat. Mus. Cat. Nos. 51597b and 51597c, respectively. dc. A dorsal valve doubtfully referred to this species, from Locality 7s, Upper Cambrian shale 4 miles south- southeast of Emigrant Peak, Silver Peak quadrangle, Nevada. U.S. Nat. Mus. Cat. No. 51593a. 132 U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL, © oe PLATE XXXIX. 133 LINGULELLA QUADRILATERALIS (Walcott) (p. 528). Figure 6. Ventral valve with outer layer of shell exfoliated, the type specimen, from Locality 91, Middle Cambrian shales at Cedar Bluff, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 51777a. 6a. Dorsal valve and side outline of united valves, associated with the specimen represented by figure 6. U.S. Nat. Mus. Cat. No. 51777b. OBOLUS CHINENSIS (Walcott) (p. 387). Figure 7. Partly exfoliated ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 52532a. 7a. Interior of a ventral valve. U.S. Nat. Mus. Cat. No. 52532b. Another specimen (Cat. No. 52532c) was used to restore certain parts of this drawing. 7b. Exfoliated dorsal valve, showing visceral area. U.S. Nat. Mus. Cat. No. 52532d. The specimens represented are all from Locality C62, Middle Cambrian limestones 2.5 miles south of Yenchuang, Sintai district, Shantung, China. LINGULELLA DAMESI (Walcott) (p. 489).4 Fiaure 8. Top and side view of a partly exfoliated ventral valve, showing outline of posterior portion of visceral area and position of the main vascular sinuses. U.S. Nat. Mus. Cat. No. 52529a. 8a. Partly exfoliated ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 52529b. 8b. Exterior of a ventral? valve. U.S. Nat. Mus. Cat. No. 52529c. 8c. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 52529d. The specimens represented are all from Locality €10, Middle Cambrian limestone about 3 miles southwest of Yenchuang, Sintai district, Shantung, China. LINGULELLA (LINGULEPIS) EROS (Walcott) (p. 551). Figures 9 and 9a. Ventral and dorsal valves restored in outline from other specimens. Locality €7, Middle Cambrian limestone 2.2 miles southwest of Yenchuang, Sintai district, Shantung, China. U.S. Nat. Mus. Cat. Nos. 52527a and 52527b, respectively. Figure 9 represents the type specimen. OxBoLus (WESTONIA) BLACKWELDERI Walcott (p. 453). Figure 10. An elongate ventral valve, the type specimen, with posterior portion broken away, from Locality C6, Middle Cambrian shaly limestone 2.5 miles southwest of Yenchuang, Sintai district, Shantung, China. U.S. Nat. Mus. Cat. No. 52540a. 10a. Short form of ventral valve associated with the shell represented by figure 10. U.S. Nat. Mus. Cat. No. 52540b. ; 10b. Exterior of a dorsal valve from Locality C2, Middle Cambrian limestone 2 miles south of Yenchuang, Sintai district, Shantung, China. U.S. Nat. Mus. Cat. No. 52541a. 10c. Enlargement of surface of a shell associated with the ventral valve represented by figure 10. U.S. Nat. Mus. Cat. No. 52540c. LINGULELLA HEBERT! Barrois (p. 505). 11. Exterior of ventral valve. lla. Exterior of dorsal valve. 11b. Cast of interior of ventral valve, the type specimen. lic. Enlargement of the outer surface. Figures 11, lla-c are copied from Barrois [1882, Pl. IV, figs. 3a-d, respectively]. The specimens represented are all from Locality 350a, Ordovician sandstone at Cape Vidio, Province of Oviedo, Spain. a Now referred to Obolus ; see p. 489. UY K cna Pare Ti ie) RPM ech lle Meets i Deo ea 4 perl 9 ake ‘eA ‘ * rr, PLATE XL. v. Visceral cavity. LINGULELLA (LINGULEPIS) ACUMINATA (Conrad) (p. 545). [Pl]. XXXIV, figs. 3, 3a-e; Pl. XLI, figs. 1, la-n; and Pl]. XLII, figs. 1, 1a-o.] Figure 1. Ventral valves, the type specimens, from Locality 338s, Upper Cambrian sandstone at High Bridge on Ausable River, Essex County, New York. Copied from Hall [1847, text fig., p. 9], who states that the figure is copied from a drawing made by Conrad. Ja. Ventral valves from Locality 338s, Upper Cambrian sandstone at High Bridge on Ausable River, Essex County, New York. Copied from Emmons’s figure [1842, text fig. 68, p. 268] of Lingula antiqua. 1b. Partly exfoliated ventral valve, showing the visceral cavity, from Locality 110, Upper Cambrian sand- stone, east side of the town of Whitehall, New York. U.S. Nat. Mus. Cat. No. 51877a. Je. Narrow ventral valve associated on the same slab of rock with figure 1b. U.S. Nat. Mus. Cat. No. 51877b. 1d and Je. Dorsal valves associated with the ventral valves represented. by figures 1b and Ic. U.S. Nat. Mus. Cat. Nos. 51877c and 51877d, respectively. if and 1g. Small ventral and dorsal valves, from Locality 109, Upper Cambrian sandstone 1.5 miles south of Deweys Bridge on the Champlain Canal, Washington County, New York. U.S. Nat. Mus. Cat. Nos. 51879a and 51879b, respectively. th. Ventral valve from Locality 76a, Upper Cambrian arenaceous limestone 1 mile north of Saratoga Springs, New York. U.S. Nat. Mus. Cat. No. 52469a. i, 1j, and 1k. Ventral valves, from Locality 76, Upper Cambrian impure limestones 4 miles west of Saratoga Springs, New York. U.S. Nat. Mus.:Cat. Nos. 51878a, 51878b, and 51878c, respectively. 11, 1m, and In. Dorsal valves associated with the specimens represented by figures li, 1j, and iis, Wis Se Nat. Mus. Cat. Nos. 51878d, 51878e, and 51878f, respectively. lo. A broad ventral valve, from Moca 392, Upper Cambrian Potsdam sandstone, Burgess, Canada. WS Nat. Mus. Cat. No. 17999a. lp and 1q. Narrow and broad form of the ventral valve, from Locality 105, Upper Cambrian limestone at Bishops Mill, Hancock County, Tennessee. U. S. Nat. Mus. Cat. Nos. 5188la and 51881b, respectively. lr and 1s. Dorsal valves associated with the ventral valves repreented by figures lp and lq. U.S. Nat. Mus. Cat. Nos. 51881c and 51881d, respectively. 136 U, S. GEOLOGICAL SURVEY FRANCES WIESER DEL. ~ PLATE XLI. i’. Outer lateral space of area. h. Central muscle sear. j- Anterior lateral muscle scar. p. Pedicle groove. v. Visceral cavity. vs. Main vascular sinus. LINGULELLA (LINGULEPIS) AcUMINATA (Conrad) (p. 545). (Pl. XXXIV, figs. 3, 3a-e; Pl. XL, figs. 1, la-s; and Pl. XLII, figs. 1, la-o.] Figure 1. Slab figured by Owen [1852, Pl. IB, fig. 8] as Lingula pinnaformis. U.S. Nat. Mus. Cat. No. 17860a. Locality 328h, Upper Cambrian sandstone at the falls of the St. Croix, Polk County, Wisconsin. la, 1b, and lec. Partly exfoliated ventral valves, showing more or less of the area and interior vascular markings. These occur in Locality 82s, Upper Cambrian sandstone at St. Croix Falls, Wisconsin. U.S. Nat. Mus. Cat. Nos. 51888a, 51888b, and 51888c, respectively. 1d and le. Ventral valves associated with the shells represented by figs. la-c. U.S. Nat. Mus. Cat. Nos. 51888d and 51888e, respectively. lf. Dorsal valve associated with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 51888f. lg. Dorsal valve associated with the specimen represented by figure la, showing the area and the central muscle scars. U.S. Nat. Mus. Cat. No. 51888g. : lh. Exfoliated dorsal valve associated with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 51888h. ; li. Ventral valve, from Locality 79b, Upper Cambrian sandstone near Hudson, St. Croix County, Wisconsin. U.S. Nat. Mus. Cat. No. 51889a. 1j, 1k, and 11. Exfoliated dorsal valves associated with the ventral valve sa pseseatie by figure la. U.S. Nat. Mus. Cat. Nos. 51888i, 51888j, and 51888k, respectively. Im. Dorsal valve associated with the specimen reprecented by figure li. U.S. Nat. Mus. Cat. No. 51889b. In. Small exfoliated ventral valve, from Locality 84, Middle Cambrian sandstone at Dresbach, Winona County, Minnesota. U.S. Nat. Mus. Cat. No. 51885a. LIncuLeLtta (LINGULEPIS) ACUMINATA MEEKI (Walcott) (p. 550). Ficures 2 and 2a. Ventral and dorsal valves from Locality 302b, Middle Cambrian limstone near Crowfoot Ridge Yellowstone National Park, Wyoming. U.S. Nat. Mus. Cat. Nos. 35206a and 35206b, respectively. Figure 2 represents the type specimen. 138 U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XLI FRANCES WIESER DEL. ~ HELIOTYPE CO., BOSTON. PAE, XaeM | PLATE XLII. a. Central lateral space of area. h. Central muscle sear. a’. Outer lateral space of area. j. Anterior lateral muscle scar. ce. Trapezoidal area, including central, middle p. Pedicle groove. lateral, and outside lateral muscle scars. v. Visceral cavity. g. Umbonal muscle sear. ys. Main vascular sinus. LINGULELLA (LINGULEPIS) ACUMINATA (Conrad) (p. 545). [Pl. XXXIV, figs. 3, 3a-e; Pl. XL, figs. 1, la-s; and Pl. XLI, figs. 1, la-n.] Figures 1 and 1d. Narrow, exfoliated ventral valve showing the visceral area. The side view, figure 1d, shows the outline of the area and the cast of the pedicle groove. Locality 355, Middle Cambrian sandstones on Red Canyon Creek, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 51894a. la and 1b. Broad ventral and dorsal valves, identified by Whitfield as Lingulepis pinnaformis. Locality 355, Middle Cambrian sandstones on Red Canyon Creek, Black Hills, South Dakota. U.S. Nat. Mus. Cat. Nos. 24588a and 24588b, respectively. le. Dorsal valve retaining a considerable amount of the laminated portion of the shell. From Locality 355d, Upper Cambrian friable reddish sandstone, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 51898a. le. Cast of the interior of a ventral valve associated with the shell represented by fig. 1c, showing area, pedicle groove, and vascular markings. U.S. Nat. Mus. Cat. No. 51898b. Another specimen (Cat. No. 51898c) was used to aid in restoring this figure. 1f. Cast of the interior of a broad dorsal valve, from the friable purple sandstones of Locality 355b, Middle Cambrian, on Castle Creek, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 1026b. 1g and 1h. Casts of the interior of broad ventral and dorsal valves. From Locality 355d, Upper Cambrian sandstone, Black Hills, South Dakota. U.S. Nat. Mus. Cat. Nos. 51898d and 51898e, respectively. liand 1}. Young shells that occur in abundance in the same layers with the specimens represented by figures Ig and lh. U.S. Nat. Mus. Cat. Nos. 51899a and 51899b, respectively. 1k, 11, and Im. Ventral valves from Locality 70, Upper Cambrian limestones on Morgans Creek, Burnet County, Texas. U.S. Nat. Mus. Cat. Nos. 51891a, 51891d, and 51891b, respectively. In. Dorsal valve associated with the ventral valves represented by figures 1k, 11, and lm. U.S. Nat. Mus. Cat. No. 51891e. lo. Cast of interior of dorsal valve, showing position of central and lateral muscle scars. From Locality 14b, Upper Cambrian limestone on Cold Creek, Llano County, Texas. U.S. Nat. Mus. Cat. No. 51892a. OsoLus (WesTONIA) ROGERSI (Walcott) (p. 463). Figure 2. Partly exfoliated ventral valve, the type specimen, illustrating the different layers forming the shell. U.S. Nat. Mus. Cat. No. 27336a. 2a. Cast of the interior of a ventral valve, showing the area and vascular markings. U.S. Nat. Mus. Cat. No. 27336b. 2b. Cast of the interior of a ventral valve in which the area extends far down the cardinal slopes. U.S. Nat. Mus. Cat. No. 27336c. 2c. Cast of the interior of a dorsal valve, showing the central position of the central muscle scars. U.S. Nat. Mus. Cat. No. 27336d. 2d. Partly exfoliated dorsal valve on which a portion of the surface of the outer shell is preserved. U.S. Nat. Mus. Cat. No. 27336e. The specimens represented are all from Locality 343, Lower Ordovician limestone pebbles on the beach near New- port, Rhode Island. Oxsotus (LinetuLopotus) sprssus (Billings) (p. 432). [Pl]. XVI, figs. 2, 2a-k.] Ficure 3. Enlargement of the surface of the specimen represented by Plate XVI, figure 2b, of this monograph. U.S. Nat. Mus. Cat. No. 51678b. 3a. Enlargement of the outer surface of the inner layer in front of the umbonal muscle scar, of the dorsal valve represented by Plate XVI, figure 2, of this monograph. U.S. Nat. Mus. Cat. No. 51678 1. The specimens represented are both from Locality 114b, Upper Cambrian sandstone, 1 mile north of Lance Cove, Great Belle Island, Conception Bay, Newfoundland. 140 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XLII FRANCES WIESER DEL. HELIOTYPE CO., BOSTON, MARIE a Bees de ite ‘y 3 heat Nae mae a : 5 ; Pana) SLIDE. | 7 Figure 1. 1 i) Ib. Hes 1d. lr. 1s. PGA Ee xan: a. Central lateral space of area. h. Central muscle scar. a’. Outer lateral space of area. j. Anterior lateral muscle scar. c. Trapezoidal area, including central, middle p. Pedicle groove. lateral, and outside lateral muscle scars. vs. Main vascular sinus. {. Flexure line of area. x. Heart-shaped cavity. LINGULELLA (LINGULEPIS) EXIGUA (Matthew) (p. 551). [Pl]. XXXII, figs. 4 and 4a] Narrow acuminate ventral valve from Locality 10t, Middle Cambrian sandstone on McLean Brook, near Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 34766a. . Slightly broader form of ventral valve than that represented by figure 1, but associated with it. U.S. Nat. Mus. Cat. No. 34766b. Broader form of ventral valve than that represented by figure la, but associated with it. Specimens showing gradations of form between figures la and 1b occur in the collections. U.S. Nat. Mus. Cat. No. 34766c. Still broader form of ventral valve intermediate between specimens represented by figures 1b and If. Associated with the specimens represented by figures 1, la~b. U.S. Nat. Mus. Cat. No. 34766e. Small ventral valve with slightly rounded instead of straight or incurved cardinal slopes, from Locality 3i, Middle Cambrian sandstone on McLean Brook, 1.5 miles west of Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 3476la. . Small narrow ventral valve laterally compressed, associated with the specimen represented by figure 1d. U.S. Nat. Mus. Cat. No. 34761b. . Large, partly exfoliated ventral valve associated with the specimen represented by figure ld. U. 8. Nat. Mus. Cat. No. 34761c. é . Elongate and attenuate ventral valve, showing cast of the interior surface, also a portion of the outer surface. It is associated with the shell represented in figure 1d. U.S. Nat. Mus. Cat. No. 34761d. . Small ventral valve with outer shell on posterior portion. It is associated with the shell represented in figureld. U.S. Nat. Mus. Cat. No. 3476le. . Small, partly exfoliated ventral valve compressed and flattened in the arenaceous shale. It isassociated with the shell represented in figure ld. U.S. Nat. Mus. Cat. No. 34761f. j. Cast of interior of a broad form of ventral valve somewhat like specimen represented by figure 1c in outline. It is associated with the specimens represented by figures 1, la-c. U.S. Nat. Mus. Cat. No. 34766d. . Small dorsal valve with strong median sinus. It is associated with the shell represented in figure 1d. U.S. Nat. Mus. Cat. No. 34761g. . Cast of the interior of a dorsal valve that hasa few pustulesonit. It isassociated with the shell represented in figure ld. U.S. Nat. Mus. Cat. No. 34761h. . Cast of part of the interior of a well-preserved dorsal valve. It is associated with the shell represented in figure 1d. U.S. Nat. Mus. Cat. No. 347611. . Fragment of arenaceous shale from Locality 10t (see fig. 1, above), with 2 group of small shells upon it. Natural size. U.S. Nat. Mus. Cat. No. 34766f. . Cast of the interior of ventral valve, showing cast of pits and the strong ridges of the main vascular canals, from Locality 3i, Middle Cambrian sandstone on McLean Brook, 1.5 miles west of Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 34761). . Part of the interior of a ventral valve associated with the specimen represented by figure lo, showing the strong ridges beneath the main vascular sinuses. U.S. Nat. Mus. Cat. No. 34761k. . Cast of interior of a ventral valve, showing heart-shaped area (x), trapezoidal area (c), and cast of vascular canal ridges (vs). Locality 10s, Middle Cambrian sandstone on McLean Brook, near Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52468b. Cast of interior of a dorsal valve associated with the specimen represented by figure 1q, showing area, visceral cavity, and portion of vascular canal ridges. U.S. Nat. Mus. Cat. No. 52468c. Another specimen (Cat. No. 34761r, from Locality 3i) was used to restore certain portions of this figure. Cast of the interior of a dorsal valve associated with the specimen represented by figure lo, showing strongly marked visceral and vascular ridges. U.S. Nat. Mus. Cat. No. 34761 1. 142 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XLIII FRANCES WIESER DEL, HELIOTYPE CO, BOSTON | roams iy as PLATE XLITI. 143 LInGULELLA (LINGULEPIS) EXIGUA (Matthew)—Continued. Fieure lt. Large, partly exfoliated dorsal valve, of the same type as the ventral valve represented by figure 1. Associated with the specimen represented by figure lq. U.S. Nat. Mus. Cat. No. 52468d. lu, lw, and 1x. Casts of the interior of dorsal valves showing variation in outline, form of visceral cavity, pitting of inner surface of valve, ete. Associated with the specimen represented by figure lq. U.S. Nat. Mus. Cat. Nos. 34761m, 34761lo, and 34761p, respectively. iv. Interior of a dorsal valve associated with the specimen represented by figure 1q, in which the pits are arranged like beads along the lines of growth. U.S. Nat. Mus. Cat. No. 34761n. ly. Part of interior of dorsal valve associated with the specimen represented by figure 1q, showing ridges on which the central muscle scars occur, main vascular canal ridges, and fine pitting of surface. U.S. Nat. Mus. Cat. No. 34761q. 1z. Cast of interior of dorsal valve in which the visceral area extends well toward the front. Locality 11z, Middle Cambrian sandstone on Big Ridge, 2 miles south of Marion Bridge, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51870a. ype ay Testa eee TBD, ad oo ; y PLATE XLIV. ° “62667? vor Bl, pr 212-10 145 i PLATE XLIV. a. Central lateral space of area. p. Pedicle groove. h. Central muscle scar. ; y. Visceral cavity. LINGULELLA (LINGULEPIS) GREGWA (Matthew) (p. 554). Ficure 1. Very perfect ventral valve preserving the entire exterior surface, from Locality 10p”, Middle Caribrian sandstones between Indian River and McPhees Brook, Canes Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51875a. Ja. Cast of the interior of a ventral valve from Locality 10p, Middle Cambrian sandstones of Division E2b, Dugald Brook, Cape Breton, Nova Scotia, showing the vascular sinuses. U.S. Nat. Mus. Cat. No. 51873a. 1b. Enlargement of a small ventral valve associated with the shell represented by figure la. U.S. Nat. Mus. Cat. No. 51873b. lc. Elongate ventral valve from Locality 10p’, Middle Cambrian sandstones on Gregwa Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51874a. 1d. Partly exfoliated ventral valve associated with the shell represented by figure la. U.S. Nat. Mus. Cat. No. 51873c. le. Small ventral valve associated with the shell represented by figure 1c, showing the cast of a long pedicle furrow and a portion of the area. U.S. Nat. Mus. Cat. No. 51874b. 1f. Cast of the interior of a very broad ventral valve associated with the shell represented by figure 1, on which a portion of the outer shell is preserved. U.S. Nat. Mus. Cat. No. 51875b. ig. Fragment of small ventral valve associated with the shell represented by figure 1, showing the area and the character of the outer surface of the shell. U.S. Nat. Mus. Cat. No. 51875c. th. Cast of part of the interior of a small dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 51878e. li. Small oval dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 518738. 1j. Transversely oval dorsal valve, preserving the outer surface, associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No.51873g. The outer surface of this shell is enlarged in figure 1p. 1k. Cast of the interior of a subtriangular dorsal valve, showing the visceral area, associated with the shell represented by figure la. U.S. Nat. Mus. Cat. No. 51873h. 11. Cast of the interior of an elongate dorsal valve associated with the shell represented by figure la. U.S. Nat. Mus. Cat. No. 51873d. 1m. Cast of the interior of an elongate dorsal valve associated with the shell represented by figure le. U.S Nat. Mus. Cat. No. 51874c. In. Cast of the interior of a dorsal valve associated with the shell represented by figure Ic. U.S. Nat. Mus. Cat. No. 51874d. The concentric lines of tubercles have been drawn in from other specimens (Cat. Nos. 51873i and 51873j from Locality 10p). lo. Enlargement of a portion of surface of a very perfectly preserved dorsal salle 12 mm. in length from Locality 18t”, Middle Cambrian sandstones of Divisions Ele and Eld on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 56792a. lp. Enlargement of the surface of the dorsal valve represented in figure 1j to show the irregular, concentric, undulating ridges. U.S. Nat. Mus. Cat. No. 51873g. LINGULELLA, (LINGULEPIS) LONGINERVIS (Matthew) (p. 555). Figures 2 and 2a. Exteriors of two small ventral valves, with nearly straight cardinal margins. Locality 13p, Middle Cambrian sandstones 40 feet above Division E2a on Dugald Brook, Cape Breton, Nova Scotia. U.S Nat. Mus. Cat. Nos. 51872a and 51872b, respectively. ; 2b. Partly exfoliated ventral valve, with incurved cardinal margins. Locality 18g, Middle Cambrian sandstones 10 feet above Division E2a, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 56977a. 2c. Interior of a broken ventral valve, showing eineeral cavity, area of central muscle scars, ete. Locality 13f, Middle Cambrian pandatones 20 feet above Division E2a, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 56974a. 2d. Exterior of a dorsal valve from Locality 10p, Middle Cambrian sandstones of Division E2b, on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 34764a. 2e. Interior of a dorsal valve from Locality 3440, Middle Cambrian sandstones of Division E2b, on Dugald Brook, Cape Breton, Nova Scotia. University of Toronto, Canada. Specimen figured by Matthew [1903, Pl. VII, fig. 6f]. The two figures should be compared. 2f and 2g. Casts of parts of interiors of dorsal valves, showing position of central scars. Locality 18d, Middle Cambrian sandstones between Divisions E2a and E2b, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. Nos. 56976a and 56976b, respectively. U. S. GEOLOGICAL SURVEY SZ; Ap yy )}\) FRANCES WIESER DEL. inne een? Sco ‘7 FIGURE PLATE XLV. ce. Trapezoidal area, including central, middle s. Median septum. lateral, and outside lateral muscle scars. v. Visceral cavity. h. Central muscle scars. vs. Main vascular sinus. j. Anterior lateral muscle scars. x. Heart-shaped cavity ps. Parietal band. LINGULELLA RADULA Matthew (p. 529). 1. Imperfect cast of the interior of a ventral valve from Locality 301x, Upper Cambrian sandstones of Divi- sion 2c of Matthew’s section, Dunns Shore, Simonds, near St. John, New Brunswick. University of Toronto, Canada. la. Cast of an interior of a ventral valve from Locality 30ly, Upper Cambrian sandstones of Division 2c, east side of Courtney Bay, St. John, New Brunswick. University of Toronto, Canada. lb. Slightly distorted ventral valve from the same locality as specimen represented by figure la. University of Toronto, Canada. lec. Cast of the interior of a distorted ventral valve, associated with specimen represented by figure la. Uni- versity of Toronto, Canada. 1d. Cast of the interior of a dorsal valve, the type specimen, showing central scars, etc., associated with the specimen represented by figure 1. University of Toronto, Canada. Figures 1, la-d, and lf are drawn from the specimens upon which Matthew based his figures [1891, Pl. XV, figs. 7a-b and 8a-e], but closer identification is impossible. FIGURE le. Cast of the interior of a distorted ventral valve from the locality represented by figure la. Museum of Comparative Zoology, Cambridge, Massachusetts. lf. Cast showing part of the interior of a dorsal valve, associated with the specimens represented by figures la-c. University of Toronto, Canada. (See note following the description of figure 1d.) lg. Small ventral valve, preserving the exterior surface and convexity of outline in an unusually perfect manner. Locality same as specimen represented by figure la. Museum of Comparative Zoology, Cambridge, Massachusetts. (See note in description of figures 1k and 11.) lh. Interior of a ventral valve, preserving the form of the heart-shaped cavity as in Obolus. Locality same as specimen represented by figure la. Museum of Comparative Zoology, Cambridge, Massachusetts. li. Cast of the interior of a ventral valve, showing the visceral cavity and main vascular sinuses with unusual clearness. Locality same as specimen represented by figure la. Museum of Comparative Zoology, Cambridge, Massachusetts. 1j. Cast of the interior of a dorsal valve, showing muscle scars, etc., beautifully preserved. Locality same as specimen represented by figure la. Museum of Comparative Zoology, Cambridge, Massachusetts. 1k and 11. Interior of dorsal valve and cast of same. Locality same as specimen represented by figure la. Museum of Comparative Zoology, Cambridge, Massachusetts. It may be that the specimens repre- sented by figures lg, 1k, and 11 represent a small species distinct from Lingulella radula. All of the specimens are more or less distorted in the arenaceous shales in which they are embedded. LINGULELLA TRIPARILIS (Matthew) (p. 536). [Text figs. 44a-1, p. 537.] 2. Broad form of ventral valve from Locality 13t’, Middle Cambrian sandstones of Division Elb on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 57018a. 2a and 2a’. Narrow form of ventral valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 57013b. 2b. Ventral valve on which a portion of the exterior surface of the shell is preserved. Associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 57013c. 2c. Cast of interior of a dorsal valve associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 57018d. 2d. Cast of interior of a dorsal valve from Locality 18t’’, Middle Cambrian sandstones of Divisions Elc and Eld, on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 57012a. 2e. Narrow form of dorsal valve associated with the specimen represented by figure 2, preserving a portion of the outer shell, with side outline. U.S. Nat. Mus. Cat. No. 57013e. Another specimen (Cat. No. 51855a, from Locality 18t) was used in restoring certain portions of this figure. 2f. Broad form of dorsal valve, associated with the specimen represented by figure 2. U.S. Nat. Mus. Cat- No. 570138. 148 U. S. GEOLOGICAL SURVEY MONOGRAPH LI BES FRANCES WIESER DEL. HELIOTYPE CO BOSTON XLV Tere ar, uy PLATE XLV. 149 LINGULELLA (LINGULEPIS) PUMILA (Matthew) (p. 556). Fiaure 3. Exterior of ventral valve, the type specimen. University of Toronto, Canada. 3a. Exfoliated dorsal valve, showing muscle scars. University of Toronto, Canada. Figures 3 and 3a are drawn from the specimens illustrated by Matthew [1903, Pl. VII, figs. 5a and 5b, respectively]. The specimens represented are both from Locality 344f, Middle Cambrian, shales of the Coldbrook of Matthew, on Dugald Brook, Cape Breton, Nova Scotia. ae a PLATE XLVI. a. Central lateral space of area. f. Flexure line of area. a’. Outer lateral space of area. p. Pedicle groove. e. Trapezoidal area, including central, middle v. Visceral cavity. lateral, and outside lateral muscle scars. Oxso.ius (WESTONIA) AURORA (Hall) (p. 451). Ficure 1. Compressed ventral valve, from which the outer shell has been exfoliated. Locality S85x, Upper Cambrian sandstone near Mazomanie, Dane County, Wisconsin. U.S. Nat. Mus. Cat. No. 5168la. The area is enlarged in figure lc. la. Cast of the interior of a compressed ventral valve associated with the specimen represented by figure 1. The visceral area (v) recalls the heart-shaped pit of Lingulella acutangula (Pl. XVII, fig. 1f). The central muscle scars were located in the area (c), but are not clearly defined. U.S. Nat. Mus. Cat. No. 51681b. lb. Compressed ventral valve associated with the specimen represented by figure 1, showing concentric and radiating lines and strize as preserved on the cast of the interior of the shell. U.S. Nat. Mus. Cat. No. 5168le. The area is enlarged in figure 1d. 1c. Enlargement of the area of figure 1. U.S. Nat. Mus. Cat. No. 51681a. 1d. Enlargement of the area of figure 1b, to show the apron-like area mentioned in the text (p. 482;. U.S. Nat. Mus. Cat. No. 51681ce. le. Cast of the exterior of a dorsal valve associated with the specimen represented by figure 1. U. &. Nat. Mus. Cat. No. 51681d. 1f. Cast of the interior of a dorsal valve associated with the specimen represented by figure 1. The shell is compressed and the area broken at x’. U.S. Nat. Mus. Cat. No. 51681e. lg. Enlargement of a portion of the central part of the surface of the shell figured in Jh, to show the irregular lamellose character of the striz. Locality 85s, Upper Cambrian sandstone at Prairie du Sac, Sauk County, Wisconsin. U.S. Nat. Mus. Cat. No. 51680a. ° lh. Part of the shell represented in figure lg, greatly enlarged by photography to illustrate the character of the outer surface. U.S. Nat. Mus. Cat. No. 51680a. 152 XLVI PE. MONOGRAPH LI U, S. GEOLOGICAL SURVEY FRANCES WIESER DEL. BOSTON HELIOTYPE CO ae PLATE XLVIL. a. Central lateral space of area. p. Pedicle groove. a’. Outer lateral space of area. ps. Parietal band. = f. Flexure line of area. s. Median septum. h. Central muscle scar. ° v. Visceral cavity. i. Transmedian muscle sear. vs. Main vascular sinus. j. Anterior lateral muscle scar. 7 Osotus (WesTonIA) ELLA (Hall and Whitfield) (p. 455). [Pl. XX XIII, figs. 3, 3a-c.] Figure 1. Ventral valve laterally compressed and flattened, from Locality 30a, Middle Cambrian siliceous shale in Big Cottonwood Canyon, southeast of Salt Lake City, Utah. U.S. Nat. Mus. Cat. No. 51691a. la. Dorsal valve associated in the same bed of shale with specimen represented by figure 1, but it is not com- pressed laterally. Neither specimen preserves any of the shell substance. U.S. Nat. Mus. Cat. No. 51691b. ; lb. Enlarged figure of the type specimen, a dorsal valve, from Locality 329, Middle Cambrian shales near Calls Fort, Boxelder County, Utah. U.S. Nat. Mus. Cat. No. 1532la. Specimen figured by Hall and Whitfield [1877, Pl. I, fig. 8] as Lingulepis ella; and by Walcott [1886b, Pl. VIII, fig. 4; and 1891a, Pl. LXVII, fig. 2b] as Lingulella ella. lc. Cast of the interior of a slightly distorted ventral valve from Locality 329e, Middle Cambrian siliceous shales of East Canyon, above Ophir, Oquirrh Range, Tooele County, Utah. U.S. Nat. Mus. Cat. No. 15820a. 1d. Another cast of the interior of a ventral valve that is associated with the specimen represented by figure 1c, but which has suffered less from distortion. U.S. Nat. Mus. Cat. No. 15320b. Specimen figured by Walcott [1898b, Pl. XXVIII, fig. 7] as Obolus (Lingulelia) ella. le and 1f. Ventral and dorsal valves of young shells associated with the shells represented by figures 1 and la. U.S. Nat. Mus. Cat. Nos. 51691c and 51691d, respectively. lg. Impression of the interior of a ventral valve from Locality 302s, Middle Cambrian shale in Last Chance Gulch, south of Helena, Montana. U.S. Nat. Mus. Cat. No. 51686a. Specimen figured by Walcott [1898b, Pl. XXVIII, fig. 5] as Obolus (Lingulella) ella. 1h and li. Interior casts of ventral and dorsal valves flattened in argillaceous shales of Locality 31, Middle Cambrian, at the Chisholm mine, near Pioche, Nevada. U.S. Nat. Mus. Cat. Nos. 15319a and 15319b, respectively. The specimen represented by figure 1i was figured by Walcott [1898b, Pl. XXVIII, fig. 8] as Obolus (Lingulella) ella. 1j. Cast of the interior of a small ventral valve with a very high area, from Locality 4g, Middle Cambrian shale 1 mile north of the forks of Eastand West Gallatin rivers, Montana. U.S. Nat. Mus. Cat. No. 51685a. 1k. Impression of the interior of a slightly distorted dorsal valve from the same locality as specimen repre- sented by figure lg, showing the characteristic muscular impressions. U. 8. Nat. Mus. Cat. No. 51686b. Specimen figured by Walcott [1898b, Pl. XXVIII, fig. 6] as Obolus (Lingulelia) ella. 11. Interior of finely preserved dorsal valve from Locality 5h, Middle Cambrian shales 2 miles southeast of Malade, Idaho. U.S. Nat. Mus. Cat. No. 51689a. 1m. Enlargement of a small individual associated with the shells represented by figures 1h and li, showing characteristic surface markings. U.S. Nat. Mus. Cat. No. 15319c. The counterpart of this specimen (Cat. No. 15319d) was used to aid in restoring certain portions of figure 1m. In. Cast of an interior of a ventral valve associated with the ventral valve represented by figure 1j. U.S. Nat. Mus. Cat. No. 51685b. lo. Enlargement by photography of the surface of a specimen associated with the shell represented by figure 1j. U.S. Nat. Mus. Cat. No. 51685c. lp. Distorted ventral valve from Locality 90, Middle Cambrian shales near Craigs Mountain, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 51634a. 154 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XLVI FRANCES WIESER DEL. HELIOTYPE CO BOSTON 21) Adv Sale vali 155 PLATE XLVIII. h. Central muscle scar. vs. Main vascular sinus. 1. Outside lateral muscle scar. x. Heart-shaped cavity. y. Visceral cavity. Oxpotus (WeEsTONIA) EUGLYPHUS (Walcott) (p. 461). Figures 1 and la. Two associated, partly exfoliated ventral valves that illustrate variation in form, and the strong lamelle of the anterior portion of the shell. Locality 74, Middle Cambrian sandstone at the head of Nunkoweap Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 27316a and 27316b, respectively. 1b. Exfoliated ventral valve associated with the specimens represented by figures 1 and 1a, showing the fine radiating strize on the inner layer of the shell. U.S. Nat. Mus. Cat. No. 27316c. le. Cast of the interior of a ventral valve, the type specimen, associated with the specimens represented by figures 1 and la, showing the character of the area, visceral cavity, and main vascular sinuses. U.S. Nat. Mus. Cat. No. 27316d. 1d. Cast of the interior of a ventral valve from Locality 74c, Middle Cambrian sandstone at the head of Lava Canyon, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 57023a. le. Cast of the interior of a dorsal valve, associated with the specimen represented by figure 1d. U.S. Nat. Mus. Cat. No. 57023b. ‘Another specimen (Cat. No. 27316e from Locality 74) was used to aid in restor- ing certain portions of this figure. lf. Enlargement of a portion of the surface near the umbo, to illustrate the irregular inosculating strie. Associated with the shells represented by figures 1 and la. U.S. Nat. Mus. Cat. No. 273168. LINGULELLA LINEOLATA (Walcott) (p. 515). FiGuRE 2. Small, obtuse ventral valve from which the shell has been largely exfoliated. Locality 73a, Middle Cam- ; brian sandstone in Chuar Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 27324a. 2a. Acuminate ventral valve associated with the shell represented by figure 2, showing a portion of the inner layers, marked by fine radiating strie. U.S. Nat. Mus. Cat. No. 27324b. 2b. Very perfect dorsal valve, the type specimen, from Locality 78, Middle Cambrian sandstones in Kwagunt Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 27325a. 2c and 2d. Partly exfoliated dorsal valves associated with the shell Pe presented by figure 2. U.S. Nat. Mus. Cat. Nos. 27324c and 27324d, respectively. 2e and 2f. Associated ventral and dorsal v: silky es from Locality 74, Middle Cambrian sandstones at the head of Nunkoweap Valley, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. Nos. 27326a and 27326b, respectively. g¢. Partly exfoliated dorsal valve, more broadly oval than usual, associated with the shell represented by figure 2b. U.S. Nat. Mus. Cat. No. 27325b. 2h. A very fine illustration of a rather large dorsal valve, associated with the shell represented by gure 2b. U.S. Nat. Mus. Cat. No. 27325c. 2i and 2j. United ventral and dorsal valves with side view, from Locality 74d, Middle Cambrian sandstone in Bass Canyon, Grand Canyon of the Colorado, Arizona. U.S. Nat. Mus. Cat. No. 51820a. 2k and 21. Casts of rather large ventral and dorsal valves that are referred to this species. They are associ- ated with the shell represented by figure 2. U.S. Nat. Mus. Cat. Nos. 27324e and 27324f, respectively. Oxzotus (WESTONIA) FINLANDENSIS Walcott (p. 462). Ficure 3. Exterior of ventral valve, the type specimen, illustrating form and surface characters. U.S. Nat. Mus. Cat. No. 35296a. 3a. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 35296b. 3b. Cast of part of interior of dorsal valve. U.S. Nat. Mus. Cat. No. 35296c. The specimens represented are all from Locality 31lx, Middle Cambrian limestone at Saltvik, Aland Island, Finland. 156 XLVINl MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. CO BOSTON HELIOTYPE PLATE XLVIII. ISP Osotus (WEsToNIA) BorTnicus (Wiman) (p. 454). Fieurss 4 and 4”. Top and side views of an almost perfectly preserved ventral valve, the type specimen. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57089a). 4a. Exterior of a partly exfoliated dorsal valve. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57089b.) 4b. Imperfect cast of the interior of a dorsal valve. Specimen in the ¢ollection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57089c). 4c. Interior of a dorsal valve. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57089d). Figures 4, 4a-c are drawn from the specimens illustrated by Wiman [1902, Pl. II, figs. 41-44, respectively] as Lingula bottnica. The specimens represented are all from Locality 311, Middle? Cambrian drift bowlder of sandstone on Eggegrund Island, Gefle Bay, Sweden. Oxso._us (WestTonIA) wimant Walcott (p. 467). Ficure 5. Exterior of ventral valve from Locality 311c, Middle? Cambrian drift bowlder No. 7 on Biludden, Gefle Bay, Sweden. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No.57090a). Type specimen, figured by Wiman [1902, Pl. IT, fig. 30] as Lingulella sp. No. 1. 5a. Exterior of ventral valve from Locality 311g, Middle? Cambrian drift bowlder No. 16 on Biludden, Gefle Bay, Sweden. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57091a). Specimen figured by Wiman [1902, PI. II, fig. 31] as Lingulella sp. No. 2. 5b. Partly exfoliated dorsal valve from Locality 311t, Middle? Cambrian drift bowlder at Ofverby, Aland Island, Finland. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57092a). Specimen figured by Wiman [1902, Pl. II, fig. 32] as y Lingulella sp. No. 7. Oxsotus (WESTONIA) ALANDENSIS Walcott (p. 451). Figure 6. Exterior of ventral valve from Locality 311j, Middle? Cambrian drift bowlder No. 28 on Biludden, Gefle Bay, Sweden. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57093a). Specimen figured by Wiman [1902, Pl. II, fig. 33] as Lingulella? sp. No. 3. : 6a. Exterior of a dorsal valve from Locality 31ly, Middle? Cambrian drift bowlder at Ytternis, Aland Island, Finland. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57094a). Type specimen, figured by Wiman [1902, Pl. II, fig. 35] as Lingulella? sp. No. 5. Oxsotus (WEsTONIA) BALTICUS Walcott (p. 453). Ficure 7. Partly exfoliated ventral valve from Locality 311t, Middle? Cambrian drift bowlder at Ofverby, Aland Island, Finland. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57095a). Specimen figured by Wiman [1902, Pl. II, fig. 34] as Lingulella? sp. No. 6. 7a. Dorsal valve from Locality 3110, Middle? Cambrian drift bowlder on Skalstenarne Island, Gefle Bay, Sweden. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57096a). Specimen figured by Wiman [1902, PI. II, fig. 37]as Lingulella? sp. No. 4. 7b. Dorsal valve from Locality 311h, Middle? Cambrian drift bowlder No. 26, on Biludden, Gefle Bay, Sweden. Specimen in the collection of the University of Upsala, Sweden; cast in the United States National Museum (Cat. No. 57097a). Type specimen, figured by Wiman [1902, Pl. IT, fig. 38] as Lingulella? sp. No. 4. we TELAINS, SUD ual a PLATE XLIX. a. Central lateral space of area. c. Trapezoidal area, including central, middle . Middle lateral muscle sear. . Outside lateral muscle scar. dove lateral, and outside lateral muscle scars. . Pedicle groove. h. Central muscle scar. . Visceral cavity. i. Transmedian muscle scar. vs. Main vascular sinus. j. Anterior lateral muscle sear. x. Heart-shaped cavity. Oxsotus (WesTonrIA) ESCASONI (Matthew) (p. 459). Ficure 1. Cast of the interior of a ventral valve, showing continuation of cast of pedicle furrow, with the central depression of the visceral area. University of Toronto, Canada. la. Interior of ventral valve, showing heart-shaped cavity and position of central muscle scars; also a strongly pitted and striated interior surface. University of Toronto, Canada. Type specimen, figured by Matthew [1901a, Pl. V, fig. 1g] as Lingulella (?) escasoni. Jaa. Enlargement of the central portion of figure 1a to show the position and size of the muscle scars, surface pits, etc. : 1b. Cast of the interior of a rather large dorsal valve. University of Toronto, Canada. Specimen is probably the one illustrated by Matthew [1901a, Pl. V, fig. 1d] as Lingulella (?) escasoni. 1c, 1d, and le. Interior of dorsal valves, showing the position of muscle scars. University of Toronto, Canada. 1f. Enlargement of the exterior surface of a shell 3 mm. long, to show radiating striz, lines of growth, and transverse undulating lines. University of Toronto, Canada. The figures are all drawn from specimens in Matthew’s figured material, but except in the cases noted (figs. la and 1b) identification is impossible. The specimens represented are all from Locality 325, Upper Cambrian shales on McAdam Shore, East Bay, Cape Breton, Nova Scofia. Osotus (WEsTONIA) STONEANUS (Whitfield) (p. 465). [Pl. XXVII, figs. 2, 2a-g.] Ficure 2. A dorsal valve from Locality 11¢, Upper Cambrian sandstone near Newton, New Jersey. 2a. Enlargement of the exterior surface of the specimen represented by figure 2. The specimen represented was figured by Weller [1903, Pl. T, fig. 6] as Lingulella stoneana. LINGULELLA TEXANA Walcott (p. 535). Ficure 3. Partly exfoliated dorsal valve, showing strong radiating striz which characterize the species. Locality 69, Upper Cambrian limestone near Honey Creek, Burnet County, Texas. U. 8. Nat. Mus. Cat. No. 51805a. 3a. Cast of a dorsal valve, the type specimen, showing the area and muscle scars. Locality 70, Upper Cam- brian limestone near Morgans Creek, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 51806a. Copied from Walcott [1908d, Pl. VIII, fig. 5]. Osotus (Westonta) reais Walcott (p. 462). Ficures 4 and 4’. Ventral valve from which the outer layer of shell has been exfoliated. Locality 64, Upper Cam- brian limestone near the Bullwhacker mine, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 51720a. ; 4a and 4a’. Partly exfoliated dorsal valve from Locality 201a, Lower Ordovician limestone east of Ham- burg Ridge, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 51542a. 4b. Dorsal valve preserving most of the outer layer of the shell, the type specimen, associated with the shell represented by figure 4a. U.S. Nat. Mus. Cat. No. 51542b. 4c. Dorsal valve associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 51720b. 4d. Enlargement of a portion of the outer surface of the shell represented in figure 4b. U. 8. Nat. Mus. Cat. No. 51542b. 160 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. XLIX ESS FRANCES WIESER DEL. HELIOTYPE CO BOSTON eae ing a a: PLATE XLIX 161 Oso.us (WESTONIA) WAsATCHENSIS Walcott (p. 466). [Text figs. 41A-F, p. 467.] Ficure 5. Compressed and crushed ventral valve. U.S. Nat. Mus. Cat. No. 57098a. 5a. Dorsal valve flattened in the siliceous shale. U.S. Nat. Mus. Cat. No. 57098b. The specimens represented are both from Locality 32x, Middle Oambrian shale in Wasatch Canyon, Boxelder County, Utah. Oxso.tus (WESTONIA) ELLA ONAQUIENSIS Walcott (p. 459). Ficure 6. Compressed, exfoliated dorsal valve, the type specimen. U.S. Nat. Mus. Cat. No. 51716a. 6a. Enlargement of the surface of another specimen to show the zigzag, transverse strie. U.S. Nat. Mus. Cat. No. 51716b. The specimens represented are both from Locality 33f, Middle Cambrian shales, Onaqui Range, Tooele County, Utah. 62667°—vo1 51, pr 2—12 iat PLATE L. a. Central lateral space of area. j. Anterior lateral muscle scar. a’. Outer lateral space of area. k. Middle lateral muscle sear. b. Boss (see text description, p. 571). 1. Outside lateral muscle scar. e. Trapezoidal area, including central, middle mr. Median ridge. lateral, and outside lateral muscle scars. p. Pedicle groove. f. Flexure line of area. ps. Parietal band. g. Umbonal muscle sear. s. Median septum. h. Central muscle scar. vs. Main vascular sinus. i. Transmedian muscle scar. x. Heart-shaped cavity. Brcra GEMMA (Billings) (p. 569). Fraures 1 and 1b. Exterior and side view of a ventral valve with the outer surface partly removed by erosion. Locality 27, Lower Cambrian limestone near Troy, Rensselaer County, New York. U.S. Nat. Mus. Cat. No. 15349a. la. Exterior of a ventral valve associated with the specimen represented by figure 1, preserving the interrupted radiating strive of the outer surface. U.S. Nat. Mus. Cat. No. 15349b. le and 1c’. Exterior of two dorsal valves, associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. Nos. 15349¢ and 15349d, respectively. Specimen figured by Walcott [1886b, Pl. X, fig. 2e] as Obolella gemma. 1d. Posterior portion of a ventral valve associated with the shell represented by figure 1, on which the con- centric and radiating lines are very strong (see fig. le). U.S. Nat. Mus. Cat. No. 15349e. le. Outer surface of a ventral valve from Locality 2b, Lower Cambrian limestone near Beman Park, Troy, New York, greatly enlarged. This may possibly be the surface of Bicia whiteavesi. U.S. Nat. Mus. Cat. No. 51900a. lf. Natural cast of interior of ventral valve from Locality 20, Lower Cambrian limestone bowlders at east entrance to Bic Harbor, Quebec. U.S. Nat. Mus. Cat. No. 14889d. lg. Natural cast of interior of ventral valve associated with the specimen represented by figure le, at Troy, New York. U.S. Nat. Mus. Cat. No.51900b. Another specimen (Cat. No. 51900c) was used to aid in restoring certain portions of this figure. th, li, and 1k. Interiors of ventral valves showing variation in area, thickening of shell, etc. They are associated with the specimen represented by figure 1f, at Bic Harbor, Canada. U.S. Nat. Mus. Cat. Nos. 14889c, 14889b, and 14889a, respectively. The specimens represented by figures li and 1k were illustrated by Walcott [1886b, Pl. X, figs. 2b and 2d, respectively] as Obolella gemma. The specimen illustrated by Walcott [1886b, Pl. X, fig. 2] is not figured in this‘ monograph. 1j. Interior of ventral valve, with thick shell growth, from Locality 27, Lower Cambrian limestone near Troy, New York. U.S. Nat. Mus. Cat. No. 15349e. Specimen figured by Walcott [1886b, Pl. X, fig. 2c] as Obolella gemma. : 11. Natural cast of a distorted dorsal valve associated with the specimen represented by figure le, at Troy. New York. U.S. Nat. Mus. Cat. No. 51900d. Im. Interior of a dorsal valve associated with the shell represented by figure 1f at Bic Harbor, Canada. U.S. Nat. Mus. Cat. No. 14889f. In. Interior of dorsal valve from Locality 2b, Lower Cambrian limestone near Beman Park, Troy, New York. U.S. Nat. Mus. Cat. No. 51900e. This drawing is based on one fairly well preserved interior, but the anterior lateral muscle scars and some other details are taken from five other associated specimens (Cat. Nos. 51900f-). Bicta wuirEAvest Walcott (p. 570). Ficures 2, 2a, and 2b. Interiors of ventral valves, showing transition from short form of ventral valve of B. gemma, figure 1k, to the typical ventral valve of B. whiteavesi, figure 2c. U.S. Nat. Mus. Cat. Nos. 35260a, 35260b, and 35260c, respectively. 2c. Interior of a ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 35260d. 2d. Natural cast of the interior of the specimen represented by figure 2c. U.S. Nat. Mus. Cat. No. 35260e. 2e. Interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 352608. The specimens represented are all from Locality 2b,-Lower Cambrian limestone near Beman Park, Troy, New York. 164 U, S. GEOLOGICAL SURVEY MONOGRAPH L! PL. L FRANCES WIESER DEL, HELIOTYPE CO., BOSTON. ledbpavdba, ILI 165 PLATE LI. f. Flexure lines. r’. Area of anterior adductor sear h. Central muscle sear. s. Median septum. i. Transmedian muscle sear. y. Visceral cavity. j. Anterior lateral muscle scar. vs. Vascular sinus. 1. Outside lateral muscle scar. ivs. Central lateral branches of vascular p. Pedicle groove. system. r. Area of posterior adductor scar. x. Heart-shaped cavity. ELKANIA DESIDERATA (Billings) (p. 562). Fictre 1. Interior of a ventral valve, showing reversed area and muscle scars. U.S. Nat. Mus. Cat. No. 51943a. la. Cast of interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51943b. 1b. Cast of interior of dorsal valve, showing main vascular sinuses with branches extended over-ceniral area. U.S. Nat. Mus. Cat. No. 51943c. ic. Cast of interior of dorsal valve, showing central area defined, but no traces of branches of main vascular sinuses. This central area has been interpreted as probably the area of attachment of muscles, by authors who have written of the species. U.S. Nat. Mus. Cat. No. 51943d. 1d. Cast of interior of a dorsal valve in which the visceral area is beautifully defined, but the vascular sinuses and the central area included within them are not defined. U.S. Nat. Mus. Cat. No. 51943e. The specimens represented are all from Locality 319a, Lower Ordovician shales, at Point Levis, Quebec. ELKanta ampreta (Walcott) (p. 562). Fictre 2. Exterior of ventral valve. This specimen can not be located and the locality number is not known. The figure, however, is a new drawing of the specimen illustrated by Walcott [1884b, Pl. I, fig. 2b] as Obolella? ambigua. 2a. Partly exfoliated dorsal valve, showing the outlines of the visceral area and main vascular sinuses on the inner lamellations of the shell. U.S. Nat. Mus. Cat. No. 24554a. Type specimen, figured by Walcott [18S4b, Pl. I, fig. 2a] as Obolella? ambigua. 2b. Interior of a dorsal valve, showing visceral area, muscle scars, and main vascular sinuses. U.S. Nat. Mus. Cat. No. 24554b. Specimen figured by Walcott [1884b, Pl. I, fig. 2c] as Obolella? ambigua. 2c. Cast of the interior of a dorsal valve in which the thickening of the shell within the lines of the main vascu- lar sinuses is greater than in any other specimen. The visceral area also extends farther forward into the valve. This variation in the forward extension of the visceral area is not infrequent in species of Obolus. U.S. Nat. Mus. Cat. No. 24554c. The specimens represented by figures 2a—-c are all from Locality 63, Lower Ordovician: limestone, northeast of Adams Hill, Eureka district, Nevada. Oxsotts (ForDINIA) BELLULUS (Walcott) (p. 428). Fictre 3. Top and side views of a partly exfoliated ventral valve irom Locality 7z, Upper Cambrian limestone, about 3 miles southeast of Emigrant Pass, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 519442. 3a. Interior of a ventral valve, the type specimen, showing central trapezoidal area at x; also main vascular sinuses, pedicle groove, etc. U.S. Nat. Mus. Cat. No. 51944a. 3b and 3c. Casts of interior of ventral valves. U.S. Nat. Mus. Cat. Nos. 51944b and 51944c, respectively. 3d. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 51944d. 3e. Interior of dorsal valve. U.S. Nat. Mus. Cat. No. 51944e. 3i. Cast of interior of dorsal valve. U.S. Nat. Mus. Cat. No. 51944i. The specimens represented by figures 3a-f are from Locality 7x, Upper Cambrian limestones about 2.5 miles southeast of Emigrant Pass, Silver Peak quadrangle, Esmeralda County, Nevada. 166 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. LI FRANCES WIESER DEL. HELIOTYPE CO BOSTON PLATE LI. 167 ELxKant ipa (Billings) (p. 563). [Pl. XXX, figs. 20 and 20a.] Ficures 4 and 4a. Top and side views of a partly exfoliated ventral valve. Geol. Survey Canada. 4b. Cast of the interior of a dorsal valve, showing elevated visceral cavity and muscle scars. Geol. Survey Canada. 4c. Interior of a ventral valve, preserving a portion of the reversed area. Geol. Survey Canada. The specimens represented are all from Locality 319i, limestone No. 2 of Billings’s section, at Point Levis, Quebec. Oxo.us (ForDINIA) GILBERTI Walcott (p. 429). Ficures 5, 5a, and 5c. Side and top views of ventral valves varying in outline and convexity. U.S. Nat. Mus. Cat. Nos. 51946a, 51946c, and 51946d, respectively. Figure 5, the type specimen, is copied from Walcott [1908d, Pl. VII, fig. 15]. 5b. Interiorof dorsal valve. U.S. Nat. Mus. Cat. No.51946b. Copied from Walcott [1908d, Pl. VII, fig. 15a}. 5d. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 51946e. The specimens represented are all from Locality 11m, Middle Camprian limestone southeast of Marjum Pass. House Range, Utah. ; SCHUCHERTINA CAMBRIA Walcott (p. 585). Ficures 6, 6’, and 6’. Exterior, side, and back views of a partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 5141 1a. 6a. Exterior of a large, partly exfoliated ventral valve with a slight median fold. U.S. Nat. Mus. Cat. No. 51411b. 6b. Cast of the interior of a ventral valve, the type specimen, showing flabelliform muscle scars. U.S. Nat. Mus. Cat. No. 51411e. 6c. Interior of the ventral valve represented by figure 6b, drawn from a cast of that specimen. U.S. Nat. Mus. Cat. No. 51411c. Parts of this figure are restored from other specimens. 6d and 6d’. Top, back, and side views of a cast of the interior of a slightly distorted ventral valve. U.S. Nat. Mus. Cat. No. 51411d. 6e. Interior of the ventral valve represented by figure 6d, obtained by making a cast of that specimen. U. S. Nat. Mus. Cat. No. 51411d. 6f. Top and side view of a cast of a dorsal valve. U.S. Nat. Mus. Cat. No. 51411e. 6g. Exterior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51411f. 6h. Cast of the interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51411¢. 6i. Interior of the ventral valve represented by figure 6h obtained by making a cast of that specimen. U. 8. Nat. Mus. Cat. No. 51411g. 6j. Cast of the interior of a dorsal valve, showing mesial area and vascular markings. U.S. Nat. Mus. Cat. No. 51411h. 6k. Enlargement of the central portion of figure 6]. 61. Cast of the posterior portion of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51411i. 6m. Interior of the posterior portion of the dorsal valve represented by figure 6 1, obtained by making a cast of that specimen. U.S. Nat. Mus. Cat. No. 51411i. The specimens represented by figures 6, 6a—m are from Locality 5k, Middle Cambrian limestones on the road to Wolsey, about 8 miles south of Neihart, Little Belt Mountains, Montana. alt Met sega AEST jap S sethey ae | badihik - kd i etn | 12) PiA TE) anil 169 PLATE LII. a. Area of dorsal valve. sh. Cast of exterior of cardinal area on each side cl. Cardinal muscle scar. of pedicle furrow. h. Central scars. y. Visceral area. p. Cast of pedicle groove. vs. Main vascular sinus. s. Median septum. DicELLoMusS PoLiTus (Hall) (p. 575). [Text figs. 16A-B, p. 314, and 49A-B, p. 576.] Figure 1. Ventral valve. Thespecimen from which this figure was drawn can not nowbe located. The locality and catalogue number are therefore unknown. Ja. Ventral valve from Locality 98, Upper Cambrian sandstone at Eau Claire, Wisconsin. U.S. Nat. Mus. Cat. No. 35211a. 1b. Exterior and side views of ventral valve from Locality 78a, Upper Cambrian sandstone on Mount Wash- ington, near Eau Claire, Wisconsin. U.S. Nat. Mus. Cat. No. 27447a. le and 1d. Casts of interiors of ventral valves associated with the shell represented by figure la. U.S. Nat. Mus. Cat. Nos. 35211b and 35211c, respectively. The specimen represented by figure 1c was figured by Walcott [1899, Pl. LX, fig. 4a]. le. Partly exfoliated ventral valve in which the visceral area extends forward of the center of the valve. Locality 82b, Upper Cambrian sandstone near Taylors Falls, Minnesota. U.S. Nat. Mus. Cat. No. 51916a. lf. Dorsal valve associated with the shell represented by figure le. U.S. Nat. Mus. Cat. No. 51916b. ig and 1h. Exteriors and side outlines of dorsal valves associated with the shell represented by figure la. U.S. Nat. Mus. Cat. Nos. 35211d and 35211e, respectively. li. Interior of a ventral valve, associated with the shell represented by figure la, showing excavated area on each side of the median line of the flattened posterior margin. U.S. Nat. Mus. Cat. No. 35211f. 1j. Interior of a ventral valve, associated with the shell represented by figure la, showing large composite muscle scars (cl), median septum (s), vascular sinuses (vs), andarea. U.S. Nat. Mus. Cat. No. 35211g. Specimen figured by Walcott [1899, Pl. LX, fig. 4]. 1k. Cast of interior of a dorsal valve associated with the shell represented by figure la. U.S. Nat. Mus. Cat. No. 35211h. 2 and 2a. Partly exfoliated ventral valves from Locality 355e, Upper Cambrian sandstone, Black Hills, South Dakota. U.S. Nat. Mus. Cat. Nos. 51924a and 51924b, respectively. 2b. Partly exfoliated ventral valve from Locality 167, Middle Cambrian sandstone 9 miles west of Custer, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 51919a. 2c. Partly exfoliated dorsal valve associated with the shells represented by figures 2 and 2a. U. 8. Nat. Mus. Cat. No. 51924c. Y 2d, 2e, and 2f. Partly exfoliated dorsal valves associated with the shell represented by figure 2b. U.S. Nat. Mus. Cat. Nos. 51919b, 51919c, and 51919d, respectively. ¢, Exterior of a ventral valve from Locality 355, Middle Cambrian sandstones on Red Canyon Creek, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 24593a. Specimen figured by Whitfield [1880, Pl. II, fig. 13] as Obolella polita. The specimen represented by figure 12 of Whitfield’s paper is not figured in this monograph. 2h. Ventral valve from Locality 355e, Upper Cambrian sandstone, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 1027a. Specimen figured by Meek and Hayden [1865, Pl. I, figs. 2a-b] as Lingulepis prima. 2i. Dorsal valve associated with the ventral valve represented by figure 2h. U.S. Nat. Mus. Cat. No. 1027b. 3. Partly exfoliated dorsal valve, from Locality 302k, Middle Cambrian limestones, near Gallatin, Montana. U.S. Nat. Mus. Cat. No. 51923a. 4, Ventral valve, broadened by distortion and partly exfoliated. U.S. Nat. Mus. Cat. No. 51913a. 4a. Dorsal valve, broadened by distortion. U.S. Nat. Mus. Cat. No. 51913b. The specimens represented by figures 4 and 4a are both from Locality 302s, Middle Cambrian shale 1.5 miles south of Helena, Montana. They are somewhat doubtfully referred to this species. Fiaure 5. Partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 5192la. 5a. Exterior view and side outline of dorsal valve. U.S. Nat. Mus. Cat. No. 51921b. 5b. Fragment of cast of interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 5192I1c. The specimens represented by figures 5, 5a-b are all from Locality 329b, Middle Cambrian limestone, collected by the Wheeler Survey in Utah. 170 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. Lil FRANCES WIESER DEL. HELIOTYPE CO BOSTON PLATE LII. I 7(Al DICELLOMUS PECTENOIDES (Whitfield) (p. 575) [Text figs. 48A-B, p. 575.] Fravure 6. A transverse, partly exfoliated ventral valve from Locality 355b, Middle Cambrian sandstone on Castle } Creek, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 24592a. Specimen figured by Whit- field [1880, Pl. II, fig. 18] as Obolus ? pectenoides. This may be the type specimen, but it can not be identified with any of Whitfield’s figures [1875, unnumbered plate, figs. 1-3]. 6a. Partly exfoliated dorsal valve associated with the shell represented by figure 6. U.S. Nat. Mus. Cat. No. 24592b. Specimen figured by Whitfield [1880, Pl. II, fig. 19] as Obolus ? pectenoides 6b. Cast of interior of a ventral valve from Locality 164, Middle Cambrian sandstone near Deadwood, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 5191la. 6c. Cast of interior of a dorsal valve associated with the shell represented by figure 6b. U.S. Nat. Mus. Cat. No. 51911b. DiceLLomus sp. undt. Walcott (p. 578). Ficures 7 and 7a. Exterior and side views of a dorsal valve, from Locality 3101, Middle Cambrian at Andrarum, Province of Christianstad, Sweden. U.S. Nat. Mus. Cat. No. 58304. 7 ibe Oey ’ Aa) we 173 PLATE LIII. ec. Trapezoidal area, including central, j. Anterior lateral muscle scar. middle lateral, and outside lateral k. Middle lateral muscle scar. muscle scars. 1. Outside lateral muscle scar. el. Cardinal scars. p. Pedicle furrow. h. Central muscle scar. y. Visceral area. i. Transmedian muscle scar. vs. Vascular sinus. DicELLomus NANus (Meek and Hayden) (p. 573). Ficures 1 and la. Exterior and side views of ventral valves varying in outline. U.S. Nat. Mus. Cat. Nos. 51903m and 51903a, respectively. 1b. Interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51903b. lc. Natural cast of an interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51903c. 1d. Interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51903d. le. Natural cast of an interior ofa ventral valve. U.S. Nat. Mus, Cat. No. 51903e. lf. Partly exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 519038. lg and lh. Exterior and side views of dorsal valves varying in outline. U.S. Nat. Mus. Cat. Nos. 51903g and 51903h, respectively. li. Interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 519031. 1j. Natural cast of interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51903). 1k. Natural cast of interior of a dorsal valve with large cardinal scars. U.S. Nat. Mus. Cat. No. 51903k. 11. Interior of a dorsal valve showing area. U.S. Nat. Mus. Cat. No. 519031. The specimens represented by figures 1, lal are from Locality 170, Middle Cambrian limestone about 10 miles south-southeast of Bald Mountain, Bighorn Mountains, Wyoming. Fieure 2. Interior of a ventral valve from Locality 355d, Upper Cambrian sandstone, Black Hills, South Dakota. U.S. Nat. Mus. Cat. No. 1025a. Type specimen, figured by Hayden [1862, fig. 2b, p. 73] as Obolella nana, and by Walcott [1899, Pl. LX, fig. 3d] as Dicellomus nanus. 2a. Partly exfoliated dorsal valve associated with the shell represented by figure 2. U.S. Nat. Mus. Cat. No. 1025b. Specimen figured by Hayden [1862, fig. 2a, p. 73] as Obolella nana, and by Walcott [1899, Pl. LX, fig. 3b] as Dicellomus nanus. 3. Exfoliated ventral valve from Locality 152a, Upper Cambrian sandstone on Dry Creek, Gallatin County, Montana. U.S. Nat. Mus. Cat. No. 51908a. 3a. Natural cast of an interior of a ventral valve from Locality 170, Middle Cambrian limestone 10 miles south- southeast of Bald Mountain, Bighorn Mountains, Wyoming. U.S. Nat. Mus. Cat. No. 51903n. 3b. Dorsal valve associated with the shell represented by figure 3a. U.S. Nat. Mus. Cat. No. 519030. 3c and 3d. Exteriors of dorsal valves associated with the shells represented by figure 3. U.S. Nat. Mus. Cat. Nos. 51908b and 51908c, respectively. DiIcELLOMUS APPALACHIA Walcott (p. 572). Fieure 4. Exterior of a ventral valve from Locality 119, Middle Cambrian limestone collected somewhere in either Jefferson or Hawkins County, Tennessee. U.S. Nat. Mus. Cat. No. 51926a. 4a. Cast of interior of a ventral valve, the type specimen, from Locality 89, Middle Cambrian limestone in Murphrees Valley, Blount County, Alabama. U.S. Nat. Mus. Cat. No. 51928a. 4b. Exterior of a ventral valve from Locality 90a, Middle Cambrian shales at Cedar Bluff, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 51939a. 4c. Dorsal valve from Locality 16, Middle Cambrian limestone in Blountsville Valley, Blount County, Ala- bama. U.S. Nat. Mus. Cat. No. 51937a. 4d. Partly exfoliated dorsal valve associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 51926b. 4e. Partly exfoliated dorsal valve, associated with the shell represented by figure 4a, showing visceral area, muscle scars, etc. U.S. Nat. Mus. Cat. No. 51928b. 4f. Partly exfoliated dorsal valve, from Locality 91, Middle Cambrian shales at Cedar Bluff, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 51936a. 4g. Partly exfoliated dorsal valve from Locality 103a, Middle Cambrian shale on the road from Rogersville to Dodson Ford, Hawkins County, Tennessee. U.S. Nat. Mus. Cat. No. 51938a. 174 U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL, HELIOTYPE CO,, BOSTON. MONOGRAPH LI PL. LII Ss we j.\y vs ¢ 175 j ay PLATE LIV. a. Central lateral space of area. i. Transmedian muscle sear. a’. Outer lateral space of area. j. Anterior lateral muscle sear. e. Trapezoidal area, including central, 1. Outside lateral muscle sear. middle lateral, and outside lateral p. Pedicle groove. muscle scars. pe. Cast of pedicle opening. f. Flexure line of area. v. Visceral cavity. h. Central muscle scar. vs. Main vascular sinus. OBOLELLA cHROMATICA Billings (p. 591). ‘Fiaure 1. Ventral valve of the usual form and outline. U.S. Nat. Mus. Cat. No. 14891a. la. Posterior view of the specimen represented by figure 1b, showing area and narrow pedicle slit. U. 8. Nat. Mus. Cat. No. 14891b. 1b and lc. Outer and side view of a ventral valve that is less elongate than specimen represented by figure 1 (see fig. la). U.S. Nat. Mus. Cat. No. 14891b. 1d. Dorsal valve, in which the structure of the shell is unusually well preserved. U.S. Nat. Mus. Cat. No. 14891c. le. Cast in limestone of the interior of a ventral valve, showing vascular markings and muscle scars. The extreme posterior portion is, unfortunately, broken away. The false pedicle furrow is too deep and strong. Itis shallow in the specimen. U.S. Nat. Mus. Cat. No. 14891d. 1f. Interior of a ventral valve that has a narrow thickening of the shell just in front of the area, corresponding to the posterior portion of the thickened shell usually present in the ventral valve of Obolella crassa beneath the visceral area. (See figs. 2g and 2i.) Geol. Survey Canada. lg. Cast in limestone of the interior of a small dorsal valve. U.S. Nat. Mus. Cat. No. 14891e. lh. Interior of a dorsal valve. The area is outlined from a specimen in the collection of the Geological Sur- vey of Canada. U.S. Nat. Mus. Cat. No. 14891f. Specimen figured by Walcott [1886b, Pl. XI, fig. lb]. The specimens represented by figures 1 and la [Walcott, 1886b, Pl. XI] are not redrawn in this monograph. li. Interior of a dorsal valve drawn from a plaster cast of a limestone cast in the collection of the Geological Survey of Canada; cast in the United States National Museum (Cat. No. 14891g). Cast figured by Walcott [1886b, Pl. X, fig. 3]; and [189la, Pl. LX-XJ, fig. 3] as Obolella circe. The specimens represented by figures 1, la—i are all from Locality 392a, Lower Cambrian limestone at L’Anse au Loup, Straits of Belleisle, Labrador. The material in the collections of the Geological Survey of Canada includes the specimens upon which Billings founded the species, but closer identification is impossible. OBOLELLA CRASSA (Hall) (p. 592). [Text fig. 14, p. 299.] Ficure 2. Exterior of a ventral valve of the usual form and outline from Locality 27, Lower Cambrian limestone in the eastern suburb of Troy, New York. U.S. Nat. Mus. Cat. No. 15348a. 2a. An unusually elongate ventral valve, with the surface characters well preserved, from Locality 2b, Lower Cambrian limestone just north of Beman Park, Troy, New York. U.S. Nat. Mus. Cat. No. 5195la. 2b. An unusually broad ventral valve associated with the shell represented by figure 2a. U.S. Nat. Mus. Cat. No. 51951b. : 2c and 2d. Exterior and side views of a dorsal valve, associated with the shell represented by figure 2a. U.S. Nat. Mus. Cat. No. 51951c. 2e. Posterior view of a ventral valve associated with the shell represented by figure 2a, showing low area and the pedicle slit. U.S. Nat. Mus. Cat. No. 51951d. 2f. Section of a ventral valve associated with the shell represented by figure 2a, naturally broken near the median line. The thickest part of the shell is over the visceral area. U.S. Nat. Mus. Cat. No. 51951e. 2g, 2h, and 2i. Interiors of ventral valves illustrating variation in the areas, vascular markings, and muscle scars. Note the narrow rounded area and the shallow median furrow in figure 2h; the inner end of the pedicle tube is shown on the specimen just beneath the inner edge of the area. Locality 2b, Lower Cambrian limestone just north of Beman Park, Troy, New York. U.S. Nat. Mus. Cat. Nos. 51951, 5195lg, and 51951h, respectively. U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. LIV FRANCES WIESER DEL, HELIOTYFE CO BOSTON PLATE LIV. WOT OBOLELLA CRASSA (Hall)—Continued. Fieure 2j. Interior of ventral valve from Locality 29a, Lower Cambrian limestone at Schodack, Rensselaer County, New York. U.S. Nat. Mus. Cat. No. 51952a. 2k. Interior of a dorsal valve associated with the specimen represented by figure 2a. U.S. Nat. Mus. Cat. No. 51951i. 21. Cast in limestone of the interior of a dorsal valve from Locality 27, Lower Cambrian limestone in the eastern suburb of Troy, New York. The exact position of the anterior lateral muscle scars in figure 21is more or less uncertain and the line from (i) indicating the transmedian scar should unite with that from (1) as in figure 21. U.S. Nat. Mus. Cat. No. 15347a. Specimen figured by Walcott [1886b, Pl. X, fig. 1c]. The other specimens illustrated [Walcott, 1886b] are not redrawn in this monograph. 2m. Interior of a dorsal valve associated with the specimen represented by figure 2a. The other specimens were used to draw in the details of the area. U.S. Nat. Mus. Cat. No. 51951j. 2n. Cast of the interior of a ventral valve associated with the shell represented by figure 2a. U.S. Nat. Mus. Cat. No. 51951k. : OBOLELLA MINOR (Walcott) (p. 596). Figure 3. Exterior of a ventral valve. U.S. Nat. Mus. Cat. No. 24628c. 3a. Cast of the interior of a ventral valve, the type specimen, showing area and cast of pedicle groove. U.S. Nat. Mus. Cat. No. 24628a. 3b. Cast of interior of ventral valve. U.S. Nat. Mus. Cat. No. 24628d. 3c. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 24628b. 3d. Cast of interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 24628e. The specimens represented are all from Locality 32, Lower Cambrian sandstone, Stissing Mountain, Dutchess County, New York. The figures (3, 3a-d) are copied from Walcott [189la, Pl. LX XII, figs. 4a, 4d, 4, 4b, and 4c, respectively]. They were then labeled ‘‘ Camarella ? minor.”’ 62667°—vou 51, pr 2—12 12 7 : ’ } 3 X . eijae rf ¢ . ' ie Pie ie ; Vat eT i ‘ ; ions F ey { ? ’ } aw ’ ie i y i eye A Q a * i } Z ‘ Es 7 . Kory - ‘ fa I ‘ La ¥ i . Paeat ’ i. : , yh ra i 7 ; : ‘ (foe 5 . if - i r hy ’ i ‘ , ; ‘ ie Poe LB * 7 wen at 1 ' j iN r " ey (a 5 } ] i BN ‘ ‘ . ’ : IMDS, JEW 179 PLATE LV. a. Central lateral space of area. pe. Cast of pedicle opening. i. Transmedian muscle scar. s. Median septum. j. Anterior lateral muscle scar. v. Visceral cavity. 1. Outside lateral scar. vs. Main vascular sinus. p. Pedicle groove. x. Heart-shaped cavity OBOLELLA ATLANTICA Walcott (p. 589). (Text fig. 51, p. 590.] Figure 1. Exterior of an unusually convex, elongate ventral valve. Locality 50, Lower Cambrian siliceous shale, Smith Sound, Trinity Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51948a. la. Cast in siliceous shale of the exterior of a ventral valve, showing surface characters of the shell. Same locality as specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 51948b. lb. Exterior of a small ventral? valve. Locality 41a, Lower Cambrian limestone beneath Topsail Head, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 56957a. le. Exterior of small dorsal valve, associated with specimen represented by figure 1b. U.S. Nat. Mus. Cat. No. 56957b. 1d. A slightly distorted dorsal valve from Locality 50, Lower Cambrian siliceous shale, Smith Sound, New- foundland. U.S. Nat. Mus. Cat. No. 51948c. le. Interior of a ventral valve associated with the shell represented by figure 1d. The pedicle furrow is too strong in the figure. On the specimen it is indicated by a slightly depressed line on each side of what is usually the pedicle furrow. This specimen is also figured in a slightly different position in text figure 51, p.590. U.S. Nat. Mus. Cat. No. 51948d. : 1f and lg. Casts of the interior of ventral valves associated with the shell represented by figure 1d. U.S. Nat. Mus. Cat. Nos. 51948e and 51948f, respectively. lh. Top and side view of cast of the interior of a ventral valve, the type specimen, from Locality 41, Lower Cambrian decomposed limestone, from Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 18322a. li. Cast of the interior of a dorsal valve, associated with specimen represented by figure lh. U.S. Nat. Mus. Cat. No. 18322b. OBOLELLA (GLYPTIAS) FAVOSA (Linnarsson) (p. 600). Ficure 2. Exterior and side view of ventral valve. U.S. Nat. Mus. Cat. No. 35264a. 2a. Exterior and side view of dorsal valve. U.S. Nat. Mus. Cat. No. 35264b. 2b. Cast of the interior of ventral valve that retains a portion of the shell. U.S. Nat. Mus. Cat. No. 35264c. 2c. Cast of the interior of small dorsal valve. U.S. Nat. Mus. Cat. No. 35264d. 2d. Outer surface of shell greatly enlarged. U.S. Nat. Mus. Cat. No. 35264e. The specimens represented by figures 2, 2a-d are from Locality 309c, Lower Cambrian sandstone at Billingen, Province of Skaraborg, Sweden. OBOLELLA MOBERGI Walcott (p. 597). Figures 3 and 3a. Exterior and side view of ventral valve, drawn from a cast taken in a natural mold in sandstone. Original in the collection of the Geological Museum, Lund, Sweden; cast in the United States National Museum (Cat. No. 35261a). 3b. Posterior view of specimen represented by figure 3, showing area and cast of pedicle slit. 3c. Cast in fine sandstone of interior of ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 35261b. 3d. Enlargement of a natural cast of a portion of the outer surface. U.S. Nat. Mus. Cat. No. 35261c. 3e. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 35261d. 3f. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 3526le. The specimens represented are all from Locality 321s, Lower Cambrian sandstone at Sularp, near Lund, Province of Malméhus, Sweden. 180 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. LV FRANCES WIESER DEL. HELIOTYFE CO., BOSTON PLATE LV. 181 OBOLELLA ? LINDsTROMI Walcott (p. 596). Figure 4. Exterior of a ventral valve, the type specimen, from Locality 321v, Lower Cambrian sandstone at Bjorkelunda, Province of Christianstad, Sweden. The specimen from which this figure was drawn can not be located. A record of the locality was, however, preserved. 4a. Cast of the interior of dorsal valve, from Locality 321s, Lower Cambrian sandstone at Sularp, near Lund, Province of Malméhus, Sweden. U.S. Nat. Mus. Cat. No. 35263a. OBOLELLA CRASSA ELONGATA Walcott (p. 595). » Ficure 5. Ventral valve, the type specimen from Locality 319b, Lower Cambrian limestone at St. Simon, Quebec, Canada. U.S. Nat. Mus. Cat. No. 14691a. 5a. Dorsal valve associated with specimen represented by figure 5. U.S. Nat. Mus. Cat. No. 14691b. OBOLELLA AsIATIcA Walcott (p. 588). Fiaure 6. Exterior of ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 52525a. 6a. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 52525b. The specimens represented are both from Locality ¢32’, Lower Cambrian limestone bowlder 1 mile south of Chonpinghien, on Nankiang River, Shensi, China. OBOLELLA WIRRIALPENSIS Etheridge (p. 599). Ficures 7 and 7’. Top and side views of ventral valve. University of Adelaide, South Australia. 7a. Exterior of dorsal valve marked by strong concentric ridges. U.S. Nat. Mus. Cat. No. 51963a. 7b. Dorsal valve. University of Adelaide, South Australia. Type specimen, figured by Etheridge [1905, Pl. XXV, fig. 2]. The specimens represented by figures 7, 7a-b are all from Locality 315d, Lower? Cambrian limestone near Wirrialpa, Flinders Range, South Australia. Re et seep ite Hk yg. J gi tae ee Co AR et ae to PLATE LVI. 183 FIGURE FIGURE PLATE LVI. el. Cardinal scars. s. Median septum. F’. Cast of foraminal tube. v. Visceral area. fa. False area. vs. Vascular sinuses. j. Anterior lateral muscle scar. x’. Cast of visceral cavity. ACROTHELE CORIACEA Linnarsson (p. 642). 1. Top and back view of ventral valve from Locality 334f, Middle Cambrian limestone on Bornholm Island, Denmark. U.S. Nat. Mus. Cat. No. 51988a. la. Interior of a ventral valve from Locality 320f, Middle Cambrian limestone at Andrarum, Province of Christianstad, Sweden, U.S. Nat. Mus. Cat. No. 18208a. lb. Cast of interior of a ventral valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 18208b. le. Cast of interior of a ventral valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 18208e. : 1d and le. Interiors of dorsal valves associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. Nos. 18208e and 18208d, respectively. 1f. Cast of interior of a dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 18208f. . Enlargement of the surface of a specimen associated with the shell represented by figure 1. U.S. Nat. Mus. Cat. No. 51983b. 1h and 1h’. Top and side views of a.small ventral valve from Locality 8w, Middle Cambrian limestones at Andrarum, Province of Christianstad, Sweden, showing the small node on each side of the apex. U.S. Nat. Mus. Cat. No. 51978a. li. Top and back view of a very small ventral valve associated with the shell represented by figure 1h, showing a central posterior node, and a small node on each side of the apex. U.S. Nat. Mus. Cat. No. 51978b. 1 o .=) ACROTHELE (REDLICHELLA) GRANULATA (Linnarsson) (p. 663). 2. Top and side views of exterior of a ventral valve from Locality 8z, Middle Cambrian limestones of the Paradoxides elandicus zone at Borgholm, Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 51991a. 2a. Interior of a ventral valve from Locality 3100, Middle Cambrian limestones of the Paradowides tessini zone at Borgholm, Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 566438a. 2b. Cast of the interior of a ventral valve from Locality 309f, Middle Cambrian shale at Borgholm, Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 23897a. 2c. Interior of a ventral valve associated with the shell represented by figure 2, showing visceral area. U.S. Nat. Mus. Cat. No. 51991b. 2d. Top and side views of exterior of a dorsal valve associated with the shell represented by figure 2. U.S. Nat. Mus. Cat. No. 51991c. 2e. Interior of a dorsal valve associated with the shell represented by figure 2. U.S. Nat. Mus. Cat. No. 51991d. : 2f. Exterior of a dorsal valve associated with the shell represented by figure 2b, showing elongate tubercles at the apex. U.S. Nat. Mus. Cat. No. 23897b. 2a, Enlargement of the surface of the specimen represented by figure 2. U.S. Nat. Mus. Cat. No. 23897b. 2h. Exterior of a dorsal valve from Locality 320b, Middle Cambrian limestones at Gudhem, Province of Skaraborg, Sweden. U.S. Nat. Mus. Cat. No. 51992a. 2i, Cast of an interior of a ventral valve associated with the dorsal valve represented by figure 2h, showing the cast of the visceral area (v), the expanded interior opening of the foraminal tube (F’), and main vascular sinuses (vs). U.S. Nat. Mus. Cat. No. 51992b. 2}. Partly exfoliated ventral valve from Locality 309f, Middle Cambrian shale at Borgholm, Oeland Island, Sweden, showing the main vascular sinuses and branches. U.S. Nat. Mus. Cat. No. 23897c. 2k. Fragment of the interior of a ventral valve associated with the shells represented by figures 2h and 2i, ereatly enlarged so as to show the outline of the visceral area. U.S. Nat. Mus. Cat. No. 51992c. 184 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. LVI FRANCES WIESER DEL. HELIOTYPE CO., BOSTON. PLATE LVI. 185 ACROTHELE (REDLICHELLA) GRANULATA (Linnarsson)—Continued. Figure 21. Cast of the interior of a dorsal valve associated with the specimen represented by figure 2). U.S. Nat. Mus. Cat. No. 23897d. 2m and 2n. Side and posterior views of a shell in which the two valves are united, associated with the shell represented by figure 2. U.S. Nat. Mus. Cat. No. 51991e. ACROTHELE INTERMEDIA Linnarsson (p. 646). Ficures 3 and 3a. Ventral valve, the type specimen, with side outline, X4. Copied from Linnarsson [1879, Pl. III, figs. 40 and 41]. 3b. Interior of a ventral valve, showing main vascular canals and branches, <4. Copied from Linnarsson [1879, Pl. III, fig. 43]. 3c. Cast of the interior of a ventral valve. Copied from Linnarsson [1879, Pl. ILI, fig. 42]. 3d. Cast of the interior of a broken dorsal valve. Copied from Linnarsson [1879, Pl. III, fig. 44]. The specimens represented by figures 3, 3a-c are from Locality 320k, Middle Cambrian limestones of the Coro- natus zone at Kiviks Esperéd, Province of Malméhus; the specimen represented by figure 3d is from Locality 320i, the same horizon, at Andrarum, Province of Christianstad; both in Sweden. JeJbyestid; JEN AUE 187 PLATE LVII. el. Cardinal scars. s. Median septum. F. Foramen. v. Visceral area. F’. Cast of pedicle tube. vs. Vascular sinus. ACROTHELE BOHEMICA (Barrande) (p. 639). Fieures land l’. Top and side views of ventral valve, the type specimen, from Locality 345¢e, Middle Cambrian shales at Mleschitz, Bohemia. Copied from Barrande [1879b, Pl. CII, figs. viz: 1A and 1B], where they are labeled Obolus ? bohemicus. Ja and la’. Top and side views of a dorsal valve associated with the ventral valve represented by figure 1. Copied from Barrande [1879b, Pl. CII, figs. vi: 2A and 2B], where they are labeled Obolus ? bohemicus. 1b. Ventral valve from Locality 345, Middle Cambrian shales on the Dlouha Hora, above the brook of Sbirov, near Skrej, Bohemia. Copied from Pompeckj [1896b, Pl. XIV, fig. 8b]. 1c. Dorsal valve from the locality represented by figure 1b. Copied from Pompeckj [1896b, Pl. XIV, fig. 11]. 1d. Interior of dorsal valve from the locality represented by figure 1b. Copied from Pompeckj [1896b, Pl. XIV, fig. 10b]. ACROTHELE MACULATA (Salter) (p. 647). [Pl. LVIL, fig. 2.] Ficure 2. Exterior of dorsal valve. 2a. Exterior of dorsal valve. oa r, Tae 2b. Cast of the interior of a dorsal valve, the type specimen. Figures 2, 2a-b are copied from Davidson [1868, Pl. XVI, figs. 1-3]; the same figures being copied by Davidson in his later work [1871, Pl. L, figs. 18.19, and 21]. Davidson states that the specimens are from Porth-y-rhaw, St. Davids, and from Gwynfynydd and Camlan, North Wales. ACROTHELE BELLAPUNCTATA Walcott (p. 636). Figure 3..Exterior of partly exfoliated ventral valve, the type specimen. U. §. Nat. Mus. Cat. No. 51972a. '' Copied from Walcott [1908d, Pl. VIII, fig. 9]. 3a. Exterior of partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 51972b. : 3b. Surface of outer layer enlarged 15 diameters. U.§. Nat. Mus. Cat. No. 51972c. A portion of the surface represented by figure 3b was illustrated by Walcott [1908d, Pl. VIII, fig. 9’] as the surface of the specimen represented by figure 3; it is, however, taken from another specimen. The specimens represented are all from Locality 8v, Lower Cambrian shales at Ringsaker, near Lake Mjésen, Province of Hedemarken, Norway. BorsFORDIA GRANULATA (Redlich) (p. 605). Ficure 4. Cast of exterior of an almost perfect specimen of the transversely oval form of the ventral valve. U.S. Nat. Mus. Cat. No. 52046s. 4a. Exterior of a longitudinally elongate oval form of the ventral valve. U.S. Nat. Mus. Cat. No. 52046a. 4b. Exterior of a transversely oval dorsal valve, preserving the two small sharp tubercles at the apex. U.S. Nat. Mus. Cat. No. 52046b. 4c. Posterior portion of a ventral valve, showing the pedicle aperture. U.S. Nat. Mus. Cat. No. 52046c. 4d. Posterior portion of a ventral valve, showing a crescentiform tubercle on each side of and a small tubercle just back of the depression at the apex; the pedicle aperture is just back of the posterior tubercle and in fact appears to come up through it. U.S. Nat. Mus. Cat. No. 52046d. 4e. Exterior view of elongate form of dorsal valve. U.S. Nat. Mus. Cat. No. 52046e. 4f and 4f’. Exterior and side view of a ventral valve intermediate in outline between the specimens repre- sented by figures 4 and 4a. U.S. Nat. Mus. Cat. No. 52046f. 4g. Cast of interior of ventral valve. U.S. Nat. Mus. Cat. No. 52046g. 188 U, S. GEOLOGICAL SURVEY MONOGRAPH LI PL. LVII FRANCES WIESER DEL. HELIOTYPE CO.. BOSTON PLATE LVII. 189 BotsFrorpdIA GRANULATA (Redlich)—Continued. Fieure 4h. Partly exfoliated ventral valve, showing the impression of the main vascular sinuses on the inner layers of the shell. U.S. Nat. Mus. Cat. No. 52046h. 4i. Cast of interior of a small ventral valve. U.S. Nat. Mus. Cat. No. 520461. 4}. Cast of interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52046). 4k. Interior of a small dorsal valve. U.S. Nat. Mus. Cat. No. 52046k. 41. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 52046 1. 4m. Interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52046m. 4n and 40. Exteriors of dorsal valves, showing variation in outline, as compared with figure 4b, and in small tubercles near the apex. U.S. Nat. Mus. Cat. Nos. 52046n and 520460, respectively. 4p. Interior of a ventral valve. U.S. Nat. Mus. Cat. No. 52046p. 4q. Exterior of one of the largest ventral valves. U.S. Nat. Mus. Cat. No. 52046q. 4r. Enlargement of surface to show granulations. U.S. Nat. Mus. Cat. No. 52046r. The specimens represented are all from Locality 15r, Middle Cambrian shale at Khussak, Salt Range, India. ACROTHELE QUADRILINEATA Pompeckj (p. 655). Freure 5. Top and side views of the type specimen, a ventral valve, from Locality 345d, Middle Cambrian shales at Skrej, Bohemia. Copied from Pompeckj [1896b, Pl. XIV, figs. 6b and 6c]. ACROTHELE PRIM#VA (de Verneuil and Barrande) (p. 654). Fiaures 6 and 6’. Top and side views of the type specimen, a ventral valve, from Locality 350, Middle Cambrian limestone near Adrados, Cantabrian Mountains, Province of Leon, Spain. Copied from de Verneuil and Barrande’s figures [1860, Pl. VIII, figs. 2 and 2a] of Discina (Orbicula) primxva. BotsrorpiA? BARRANDEL Walcott (p. 602). Ficure 7. Dorsal view of the type specimen, showing apex of ventral valve, from Locality 350, Middle Cambrian limestone near Adrados, Cantabrian Mountains, Province of Leon, Spain. 7a and 7b. Posterior and side views of the specimen represented by figure 7. Figures 7, 7a-b are copied from de Verneuil and Barrande’s figures [1860, Pl. VIII, figs. 5, 5a—b] of “ Brachiopode, nouy. gen.”’ : JPJve sd. JE EGE 191 PLATE LVIII. el. Cardinal sears. h. Central muscle sear. F. Foramen. s. Median septum. F’. Cast of foraminal tube. y. Visceral area. fa. False area. vs. Vascular sinuses. ACROTHELE PRETIOSA (Billings) (p. 652). Fiaures | and la. Exteriors of crushed and slightly distorted ventral valves. U.S. Nat. Mus. Cat. Nos. 52004a and 52004b, respectively. : 1b. Partly exfoliated and compressed ventral valve. U.S. Nat. Mus. Cat. No. 52004c. le. Exterior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52004d. 1d. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52004e. le. Interior of dorsal valve. U.S. Nat. Mus. Cat. No. 52004f. lf. Cast of interior of a dorsal valve, showing median septum extending well toward the front margin. U.S. Nat. Mus. Cat. No. 52004¢. lg. Interior of dorsal valve. U.S. Nat. Mus. Cat. No. 52004h. The specimens represented are all from Locality 220a, Ordovician shales at the Grand Trunk railroad bridge over Chaudiere River, Quebec, Canada. ACROTHELE MACULATA (Salter) (p. 647). [Pl. LVIL, figs. 2, 2a-b.] Fiaure 2. Exterior of distorted and compressed ventral valve from Locality 318h, Middle Cambrian Menevian shales of St. Davids, South Wales. U.S. Nat. Mus. Cat. No. 51993a. ACROTHELE DECIPIENS Walcott (p. 644). Figure 3. Exterior of ventral valve with side and transverse outline. U.S. Nat. Mus. Cat. No. 26435b. 3a. Partly exfoliated ventral valve, the type specimen, with the rim of the foraminal aperture broken off. U.S. Nat. Mus. Cat. No. 26435a. Specimen figured by Walcott [1897b, Pl. LX, fig. 2]. 3b. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 26485c. 3c. Interior of a compressed dorsal valve. U.S. Nat. Mus. Cat. No. 26435d. 3d. Cast of an interior of a distorted dorsal valve. U.S. Nat. Mus. Cat. No. 26435e. The specimens represented are all from Locality 50, Lower Cambrian shale, 1.125 miles north of Stoner, York County, Pennsylvania. ACROTHELE NiTipDA (Ford) (p. 650). Fiaure 4. Exterior of the type specimen; a dorsal valve, from Locality 27, Lower Cambrian limestone in the eastern suburb of Troy, New York. U.S. Nat. Mus. Cat. No. 15353a. Specimen figured [Walcott, 1886b, Pl. XI, fig. 2] as Obolella nitida. 4a. Interior of dorsal valve associated with the specimen represented by figure 4. U.S. Nat. Mus. Cat. No. 15353b. ACROTHELE BELLULA Walcott (p. 637). Ficure 5. Exterior of a small ventral valve, the type specimen, from Locality 90x, Middle Cambrian siliceous nodules in Coosa Valley, Cherokee County, Alabama. U.S. Nat. Mus. Cat. No. 26436a. Another specimen (Cat. No. 26436b) was used in restoring certain portions of this figure. Copied from Walcott [1897b, Pl. LX, fig. 4]. 5a. Cast of the interior of a slightly distorted ventral valve from Locality 94x, Middle Cambrian shale near Givens Mill, Cowan Creek, Cherokee County, Alabama. A portion of the shell is preserved near the apex. U.S. Nat. Mus. Cat. No. 56602a. Copied from Walcott [1897b, Pl. LX, fig. 4a]. 5b. Natural cast of the foraminal tube of a specimen associated with the shell represented by figure 5. U.S. Nat. Mus. Cat. No. 26436c. 192 - U, S. GEOLOGICAL SURVEY FRANCES WIESER DEL. HELIOTYPE CO., BOSTON. MONOGRAPH LI PL. LVIII PLATE LVIII. 193 ACROTHELE BELLULA Walcott—Continued. Figure 5c. Enlargement of the cast of the interior of a ventral valve associated with the shell represented by figure 5 U.S. Nat. Mus. Cat. No. 26436d. Copied from Walcott [1897b, Pl. LX, fie. 4b]. In this figure the line indicating the cardinal scar is extended a little too far. It should have stopped before reaching the depression. 5d. Cast of the posterior portion of the interior of a ventral valve associated with the shell represented by figure 5. U.S. Nat. Mus. Cat. No. 26436e. In this figure the line indic ating the cardinal scar is extended a little too far. It should have stopped before reaching the depression. 5e. Cast of the interior of a small ventral valve associated with the shell represented by figure 5, showing vascular sinuses. U.S. Nat. Mus. Cat. No. 26436f. 5f. Interior of a dorsal valve drawn from a cast of the specimen represented by figure 5g, showi ing the area, median septum, and diverging vascular sinuses. U.S. Nat. Mus. Cat. No. 26436g. nother specimen (Cat. No. 26436h) was used in restoring certain portions of this figure and of figure 5g. Copied from Walcott [1897b, Pl. LX, fig. 4c]. . Natural cast of the interior of a dorsal valve from Locality 90x, Middle Cambrian siliceous nodules, Coosa Valley, Cherokee County, Alabama. A cast of this specimen is represented by figure 5f. U.S. Nat. Mus. Cat. No. 264362. Copied from Walcott [1897b, Pl. LX, fig. 4d]. 5h. Cast in shale of the interior of a dorsal valve from Locality 94x, Middle Cambrian shales near Givens Mill, Cowan Creek, Cherokee County, Alabama. The cardinal muscle scar is drawn too far away aon the median line. It should be about the length of the scar from the median line. U.S. Nat. Mus. _ (Cat. No. 56602b. Copied from Walcott [1897b, Pl. LX, fig. 4e]. or isi) ACROTHELE BERGERONI Walcott (p. 638). Ficures 6 and 6a. Exteriors of compressed and slightly distorted ventral valves. U.S. Nat. Mus. Cat. Nos. 51975b and 51975c, respectively. 6b. Cast of the interior of a compressed and distorted ventral valve. U.S. Nat. Mus. ear No. 51975d. 6c. Cast of the interior of a dorsal valve, the type specimen, flattened in the shale. U.S. Nat. Mus. Cat. No. 51975a. Copied from Walcott (1908d, Pl. VIII, fig. 11]. The specimens represented are all from Locality 342, Middle Cambrian shales in Montagne Noire, Coulouma, Hérault, France. 62667°—vot 51, pr 2—12-_13 ki i ty a fe it > a a . PLATE LIX. a. Area. s. Median septum. el. Cardinal sears. v. Visceral area. F!, Cast of foraminal tube. vs. Vascular sinus. BorsrorDiaA C#®LATA (Hall) (p. 603). [Pl. LIX, figs. 3, 3a-b.] Fietre 1. Partly exfoliated, broken ventral valve from Locality 20, Lower Cambrian limestone bowlders at entrance FIGURE FIGURE to Bic Harbor, Quebec, Canada. U.S. Nat. Mus. Cat. No. 35259a. la. Fragment of a large ventral valve from Locality 2b, Lower Cambrian limestone north of Beman Park, near Troy, New York. U.S. Nat. Mus. Cat. No. 52040a. 1b. Top, side, and back views of a ventral valve associated with the shell represented by figure la, showing the foraminal aperture. U.S. Nat. Mus. Cat. No. 52040b. 1c. Broad form of ventral valve from Locality 27, Lower Cambrian limestone in the eastern suburb of Troy, New York. U.S. Nat. Mus. Cat. No. 15325a. Specimen figured [Walcott, 1886b, Pl. VII, fig. lb] as Lingulella cxlata. 1d. Small ventral valve associated with the shell represented by figure 1. U.S. Nat. Mus. Cat. No. 35259b. le. Cast of part of the interior of a ventral valve from Locality 2p, Lower Cambrian limestone a little west of Bic, Quebec, Canada. U.S. Nat. Mus. Cat. No. 56874a. 1f. Interior of a small ventral valve from Locality 35a, Lower Cambrian limestone on Bald Mountain, Washing- ton County, New York. U.S. Nat. Mus. Cat. No. 52037a. 1g. Fragment of the interior of a ventral valve from Locality 29a, Lower Cambrian limestone at Schodack, Rensselaer County, New York. U.S. Nat. Mus. Cat. No. 15323a. s lh. Enlargement ofa portion of the exterior surface of a ventral valve associated with the specimen represented by figurel. U.S. Nat. Mus. Cat. No. 35259c. li. Partly exfoliated dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 52040c. 1j. Posterior portion of a dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 52040d. 1k. Cast of the posterior portion of the interior of a dorsal valve associated with specimen represented by figure la. U.S. Nat. Mus. Cat. No. 52040e. 11. Partly exfoliated dorsal valve from Locality 35, Lower Cambrian limestone 1.5 miles north of Bald Moun- tain, Washington County, New York. U.S. Nat. Mus. Cat. No. 17457a. Im. Partly exfoliated dorsal valve associated with the specimen represented by figure la, showing cast of the median sepium and main vascular sinuses. U.S. Nat. Mus. Cat. No. 52040f. In. Fragment of a cast of the interior of a dorsal valve. The true outline of this specimen and the locality are unknown. Am. Mus. Nat. Hist., New York. : Jo. Enlargement of surface of a dorsal valve associated with the specimen represented by figure Ie. U.S. Nat. Mus. Cat. No. 15325b. Specimen figured [Walcott, 1886b, Pl. VII, fig. 1d] as Lingulella czxlata. 1p and 1p’. Thin section of limestone containing many shells of the species from Locality 2b, Lower Cambrian limestone north of Beman Park, Troy, New York. U.S. Nat. Mus. Cat. No. 52040g. lq. Exfoliated ventral valve showing cast of pedicle opening and visceral cavity, from Locality 29a, Lower Cambrian limestone at Schodack, Rensselaer County, New York. U.S. Nat. Mus. Cat. No. 15323b. MicKWITzIA MONILIFERA (Linnarsson) (p. 330). [PI. VI, figs. 1, la-p.] 2. Top and side views of the posterior portion of a ventral valve from Locality 396v, Lower Cambrian sandstone below the cement factory on Kunda Brook, Government of Esthonia, Russia. U.S. Nat. Mus. Cat. No. 51522a. BorsrorDiA CLATA (Hall) (p. 603). [Pl. LIX, figs. 1, la-q.] 3 and 3a. Top and back views of a ventral valve from Locality 39a, Lower Cambrian limestone north of Easton Station, Washington County, New York. U.S. Nat. Mus. Cat. No. 52039a. 3b. Interior of a dorsal valve from Locality 38, Lower Cambrian limestone 3 miles west of South Granville, Washington County, New York. U.S. Nat. Mus. Cat. No. 52038a. 196 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. LIX FRANCES WIESER DEL. 5 HELIOTYPE CO. BOSTON PLATE LIX. 197 ACROTHELE YORKENSIS Walcott (p. 661). Fieure 4. Exterior of the type specimen, a distorted, broken ventral valve, from Locality 48d, Middle Cambrian shales in railroad cut at York, Pennsylvania. U.S. Nat. Mus. Cat. No. 5203la. Copied from Walcott [1908d, Pl. IX, fig. 10]. 4a and 4b. Compressed, exfoliated dorsal valves associated with the specimen represented by figure 4. U.S. ; Nat. Mus. Cat. Nos. 52031b and 52031c, respectively. ACROTHELE PANDERI Walcott (p. 651). Fiaures 5 and 5’. Exterior and side views of a ventral valve, the type specimen, from Locality 4v, Lower Cambrian shales on Gordon Creek, Ovando quadrangle, Montana. U.S. Nat. Mus. Cat. No. 52003a. 5a. Exterior of ventral valve associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 52003b. 5b. Exterior of ventral valve from Locality 5j, Lower Cambrian shales 6 miles west-northwest of Scapegoat Mountain, Coopers Lake quadrangle, Montana. U.S. Nat. Mus. Cat. No. 52002a. 5c. Partly exfoliated dorsal valve associated with the shell represented by figure 5b. U.S. Nat. Mus. Cat. No. 52002b. atte eee fan ee ca" 4 J fy j ; ip te mt a Agi oda tif SAME iy a! Meets dats’ ee PDs sis Ne ae Je 3 ies pT aks ei SNe ALE : FER ee a CAE AT it RRA ire ot a" Me tie CNTY Se. +3 tg ct ate “th haha u Py / ; v v Ee J Bi srace Co ce » } 4 pl aie ee 7) wt ; rr rah! - OT ere tr ane ed Seid are) veh 5 ral y i IE AM Xe 199 PLATE LX. el. Cardinal scar. j. Anterior lateral muscle scar. fa. False area. s. Median septum. h. Central muscle scar. ‘ vs. Vascular sinus. ACROTHELE suBsIDUA (White) (p. 656). [Pl. LX, fig. 8.) Figure 1. Interior of a ventral valve from Locality 4 (?), drift pieces believed to be from the Wheeler formation, near Antelope Springs, House Range, Utah, showing outline of false area. U.S. Nat. Mus. Cat. No. 15435a. Type specimen, figured by White [1877, Pl. I, fig. 3a] as Acrotreta? subsidua. la. Exterior of ventral valve from Locality 163, Middle Cambrian Spence shale member of Ute limestone, Spence Gulch, 15 miles west of Montpelier, Idaho. U.S. Nat. Mus. Cat. No. 52015a. 1b. Exterior of an exfoliated ventral valve associated with the specimen represented by figure la, showing several radiating ribs. U.S. Nat. Mus. Cat. No. 52015b. le. Exterior of a small ventral valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 52015c. 1d. Almost perfect ventral valve in the Langston limestone, Locality 5b, 2 miles southeast of Malade, Idaho. U.S. Nat. Mus. Cat. No. 52014a. le. A cast of the interior of a ventral valve associated with the specimen represented by figure 1d. U.S. Nat. Mus. Cat. No. 52014b. lf. Cast of the interior of a ventral valve associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 52018a. lg. Exterior of a dorsal valve associated with the specimen represented by figure Id. U.S. Nat. Mus. Cat. No. 52014c. th, li, and 1j. Exteriors of dorsal valves associated with the ventral valve represented by figure la. U.S. Nat. Mus. Cat. Nos. 52015d, 52015e, and 52015f, respectively. 1k. Interior of a dorsal valve associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 15436a. 11. Interior of a dorsal valve, showing visceral area, and muscle scars on the side of the median ridge. Associ- ated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 52018b. Im. Cast of interior of a dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. Cat. No. 52015g. In. Cast of interior of a dorsal valve associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 15435b. Specimen figured by White [1877, Pl. I, fig. 3d] as Acrotreta ? subsidua. lo. Enlargement of the apex of a ventral valve 7 mm. in length on which the tubercles are small and the pedicle aperture large. Locality 30g, Middle Cambrian Marjum limestone in ridge east of Wheeler Amphitheater, House Range, Utah. U.S. Nat. Mus. Cat. No. 52016a. ACROTHELE DICHOTOMA Walcott (p. 644). Figure 2. Exfoliated ventral valve from Locality 58, Middle Cambrian Secret Canyon shale in either New York or Secret Canyon, Eureka district, Nevada, showing false area, main vascular sinuses, and apical callosity. U.S. Nat. Mus. Cat. No. 24595a. Type specimen, figured by Walcott [1884b, Pl. IX, fig. 11]. ACROTHELE SPuRRI Walcott (p. 656). Ficure 3. Top view of the type specimen, which is a partly exfoliated ventral valve, from Locality 31a, Lower Cambrian limestone near Pioche, Nevada. U.S. Nat. Mus. Cat. No. 15344a. Copied from Walcott [1908d, Pl. VIII, fig. 14]. That figure was redrawn from the specimen illustrated by Walcott [1886b, Pl. IX, fig. 4] as Acrothele subsidua. 3a and 3b. Back and side views of a partly exfoliated ventral valve associated with the specimen represented by figure 3. U.S. Nat. Mus. Cat. No. 15344b. Copied from Walcott [1908d, Pl. VIII, figs. 14” and 14’]. 3e. Exterior of an exfoliated dorsal valve associated with the specimen represented by figure 3. U.S. Nat. Mus. Cat. No. 15344c. 200 PL. LX MONOGRAPH LI U. S. GEOLOGICAL SURVEY RANCES WIESER DEL, CO BOSTON HELIOTYRE — PLATE LX. 201 ACROTHELE GAMAGEI (Hobbs) (p. 645). Ficures 5 and 5’. Top view and side outline of a ventral valve 5a. Cast of the interior of a ventral valve U.S. Nat. Mus. Cat. No. 5b and 5b’. U.S. Nat. Mus. Cat. No. 51986b. Partly exfoliated specimen of a dorsal valve and side outline of same. of Comparative Zoology; cast in the United States National Museum dc. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51986c. The specimens represented are all from Locality 5, Middle Cambrian siliceous shale on Hayward Creek, Braintree, Massachusetts. 51986a. Original in the Museum (Cat. No. 51987a). ACROTHELE WOODWORTHI Walcott (p. 661) FIGure 6 . Top, back, and side views of a cast made from the outer surface of a natural mold from Locality 326c, Lower Cambrian limestone at Nahant, Essex County, Massachusetts. Type specimen in the col- lection of the Boston Society of Natural History; cast in the United States National Museum (Cat No. 52030a). Copied from Walcott [1908d, Pl. IX, fig. 11]. ACROTHELE TURNERI Walcott (p. 660). Ficures 7 and 7’ Top and side views of a partly crushed ventral valve, the type specimen, from Locality 7r, Middle Cambrian shales 4 miles south-southeast of Emigrant Peak, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 52028a. Copied from Walcott [1908d, Pl. IX, figs. 12 and 12/]. 7a. Exterior of a compressed dorsal valve associated with the specimen represented by figure 7 U.S. Nat. Mus. Cat. No. 52028b. ACROTHELE SUBSIDUA (White) (p. 656). [Pl. LX, figs. 1, 1a-o.] Figure 8. Large compressed ventral valve from Locality 14s, Middle Cambrian Ogugopsis zone on Mount Stephen, British Columbia. U.S. Nat. Mus. Cat. No. 24063a. ACROTHELE SUBSIDUA HERA Walcott (p. 659). Ficures 9 and 9’. Top and side views of an exfoliated ventral valve, the type specimen, showing the concentric striz and radiating ridges on the inner layers of the shell. From Locality 31a, Lower Cambrian limestone near Pioche, Nevada. U.S. Nat. Mus. Cat. No. 52024a. Copied from Walcott [1908d, PI. VIII, figs. 15 and 157]. Farell ee ce eer Py, S /sagpa hehe LA Loc, | PLATE LXI. cel. Cardinal sears. s. Median septum. F’. Cast of foraminal tube. vs. Vascular sinuses. fa. False area. ACROTHELE MATTHEW! (Hartt) (p. 647). Ficure 1. Ventral valve from Locality 301j, Middle Cambrian, St. John formation at Ratcliffs Millstream, St. John County, New Brunswick. Specimen figured by Walcott [1884a, Pl. I, fig. 4a], who states that it was labeled by Hartt as No. 342, Obolus (Discina) nitidus, nov. sp. Ja. Dorsal valve from Locality 301k, Middle Cambrian, St. John formation at St. John, New Brunswick. Type specimen, figured by Hartt [1868, fig. 221, p. 644], and by Walcott [1884a, Pl. I, fig. 4]. 1b. Top and side views of an interior cast of a ventral eli e from Locality 3, Upper Cambrian limestones on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51994a. le. Cast of the interior of a compressed ventral valve associated with the shell represented by figure 1b, show- ing vascular canals. U.S. Nat. Mus. Cat. No. 51994b. 1d. Interior of a ventral valve from Locality 6n, Middle Cambrian shales on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51996a. le. Exterior of a ventral valve from Locality 6g, Middle Cambrian limestone at CEOS Arm Harbor, Trinity Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51995a. 1f. Interior of a dorsal valve associated with the shell represented by figure 1d. U.S. Nat. Mus. Cat. No. 51996b. 1g. Interior of a dorsal valve from Locality 301j, Middle Cambrian shales on Ratcliffs Millstream, St. John County, New Brunswick. U.S. Nat. Mus. Cat. No. 18170a. ACROTHELE MATTHEWI ERYX Walcott (p. 649). Figure 2. Top and side views of a partly exfoliated ventral valve, the type specimen, from Locality €4, Middle Cambrian limestone, Kiulung group, 3 miles southwest of Yenchuang, Sintai district, Shantung, China. U.S. Nat. Mus. Cat. No. 52520a. ACROTHELE MATTHEW! LATA Matthew (p. 649). Ficure 3. Interior of a crushed dorsal valve from Locality 301a, Middle Cambrian sandstones of Division 1b3 on Han- ford Brook, St. John County, New Brunswick. University of Toronto, Canada. Type specimen, figured by Matthew [1886, PI. V, figs. 17 and 17a] and by Hall and Clarke [1892c, P1. III, figs. 26-28]. ACROTHELE PRIMA CosTATA (Matthew) (p. 653). Fieure 4. Top view of a broken ventral valve with numerous cost, from Locality 2h, Middle Cambrian sandstones of Division 1b2 on Hanford Brook, St. John County, New Brunswick. U.S. Nat. Mus. Cat. No. 52010a. 4a. A crushed ventral valve with three coste, associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 52010b. 4b. Interior of a broken dorsal valve associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 52010c. 4c. Interior of a dorsal valve from Locality 6n, Middle Cambrian shales on Manuels Brook, Conception Bay, Newfoundland. U.S. Nat. Mus. Cat. No. 51984a. 4d. Enlargement of the outer surface of a specimen associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 52010d. 204 PL. LXI MONOGRAPH LI U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. ELIGTYPE CO BOSTON nH ‘ ; | B q PLATE LXI. 205 ACROTHELE MATTHEWL MULTICOSTATA Matthew (p. 650). Fiagure 5. Top and side views of a ventral valve preserving the outer surface from Locality 21, Middle Cambrian shale at the base of the Paradoxides zone on Hanford Brook, St. John County, New Brunswick. U.S. Nat. Mus. Cat. No. 56633a. 5a. Partly exfoliated ventral valve, with apex broken off. Locality 2t, Middle Cambrian shales at Hastings Cove on Kennebecasis Bay, St. John County, New Brunswick. U.S. Nat. Mus. Cat. No. 52000a. 5b. Fragment showing the numerous costee. University of Toronto, Canada. (Locality unknown.) 5e. Exfoliated dorsal valve associated with the specimen represented by figure 5a. U.S. Nat. Mus. Cat. No. 52000b. ACROTHELE PRIMA (Matthew) (p. 653). [Pl LXIL, fig. 2. Figure 6. Top view of a small ventral valve from Locality 2g, Middle Cambrian sandstones of Division 1b1 of Matthew’s Protolenus zone, Hanford Brook, St. John County, New Brunswick. University of Toronto, Canada. Type specimen, figured by Matthew [1886, Pl. V, figs. 16 and 16a] as Acrothele matthewi prima. The specimen has been figured and refigured; see page 653 for record. 6a. Natural cast of the exterior of a ventral valve from Locality 2i, Middle Cambrian limestone of Division 1b3 on Hanford Brook, St. John County, New Brunswick. U.S. Nat. Mus. Cat. No. 56638a. 6b. A ventral valve with a cast of the exterior of a dorsal valve beside it. Associated with the specimen repre- sented by figure 6a. U.S. Nat. Mus. Cat. No. 56638b. ACROTHELE AviA Matthew (p. 634). (Pl. LXII, figs. 1, la-k.] Figure 7. Exterior of a ventral valve from Locality 344b, Middle Cambrian shales of Division E3d of Matthew’s Etcheminian, Dugald Brook, Cape Breton, Nova Scotia. University of Toronto, Canada. Speci- men figured by Matthew [1902b, Pl. XVII, fig. 2a]. 7a. Interior of a broken ventral valve from Locality 13n’, Middle Cambrian shales of Division E3e of Matthew’s Etcheminian, Dugald Brook, Cape Breton, Nova Scotia. University of Toronto, Canada. Type specimen, figured by Matthew [1899b, PI. IIT, fig. 1c]. 7b. Interior of a dorsal valve from the locality represented by figure 7a. University of Toronto, Canada. Specimen figured by Matthew [1899b, Pl. III, fig. 14]. AT ILO 207 PLATE LXII. c. Area. j. Anterior lateral muscle scar. el. Cardinal scar. k. Middle lateral muscle scar. F’. Cast of foraminal tube. 1. Outside lateral muscle scar: h. Central muscle sear. ys. Vascular sinus. ACROTHELE AVIA Matthew (p. 634). (Pl. LXI, figs. 7, 7a-b.] Ficure 1. Top view of a typical form of the ventral valve from Locality 13n’, Middle Cambrian sandstones of Division B3e of Matthew’s section, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 56598a. la. Top view of a ventral valve nearly circular in outline from Locality 13d’’, Middle Cambrian sandstones 10 feet below top of Division E2a of Matthew’s section, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 56601a. 1b. Laterally compressed ventral valve from Locality 181’, Middle Cambrian sandstones of Deion E3a on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 51970a. lc. Partly exfoliated ventral valve from Locality 18m, Middle Cambrian sandstones of Division E3f on Gillis Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 56596a. The surface of this specimen is enlarged in figure 1}. 1d. Exfoliated ventral valve (locality unknown). » University of Toronto, Canada. le. Fragment of the interior of a ventral valve associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 56598b. 1f. Cast of interior of dorsal valve, from Locality 18n, Middle Cambrian sandstones of Division E3f of Mat- thew’s section, Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 56597a. 1g. Interior of dorsal valve associated with the specimen represented by figure 1c. U.S. Nat. Mus. Cat. No. 56596b. th. Interior of a compressed dorsal valve placed with the specimens from Locality 18m; the exact locality is, however, unknown. U.S. Nat. Mus. Cat. No. 56596c. li. Exfoliated dorsal valve from Locality 344b, Middle Cambrian shales of Division E3d of Matthew’s Etcheminian, Dugald Brook, Cape Breton, Nova Scotia. University of Toronto, Canada. Specimen fizured by Matthew [1902b, Pl. XVII, fig. 2b]. 1j. Enlargement of a portion of the surface of the specimen represented by figure 1c. 1k. Posterior portion of a ventral valve showing the apex. Associated with the specimen represented by figure Ib. U.S. Nat. Mus. Cat. No. 51970b. ACROTHELE PRIMA (Matthew) (p. 653). [Pl. LXI, figs. 6, 6a-b.] Ficure 2. Partly exfoliated ventral valve from Locality 13t, Middle Cambrian shaly sandstones of Division E1b on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52009a. ACROTHELE PROLES Matthew (p. 654). Ficure 3. Exterior of a slightly compressed ventral valve from Locality 18m, Middle Cambrian shaly sandstones of Division E3f on Gillis Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52011a. 34. Portion of a dorsal valve associated with the specimen represented by figure 3. U. S. Nat. Mus. Cat. No. 52011b. 3b. Interior of a fragmentary ventral valve associated with the specimen represented by figure 3. U.S. Nat. Mus. Cat. No. 52011c. 3c. Interior of a small slightly distorted ventral valve associated with the specimen represented by figure 3. U.S. Nat. Mus. Cat. No. 52011d. 3d. Partly exfoliated dorsal valve associated with the specimen represented by figure 3. U.S. Nat. Mus. Cat. No. 52011e. 3e. Partly exfoliated dorsal valve, showing vascular markings on the inner layers of the shell. Locality 13n, Middle Cambrian shaly sandstones of Division E3f on Dugald Brook, Cape Breton, Nova Scotia. U.S. Nat. Mus. Cat. No. 52012a. 208 U, S. GEOLOGICAL SURVEY aRAPH FRANCES WIESER DEL. HELIOTYPE CO., BOSTON. ee PLATE LXII. 209 ACROTHELE PROLES Matthew—Continued. Fieure 4. A cast of the exterior of the ventral valve, preserving a portion of the shell. From Locality 13m, Middle Cambrian sandstone of Division E3f of Matthew’s Etcheminian, Gillis Brook, Cape Breton, Nova Scotia. University of Toronto, Canada. Type specimen, figured by Matthew [1902b, Pl. XVII, fig. 3a]. 4a. Fragment of the interior of a dorsal valve (locality unknown). University of Toronto, Canada. The specimen from which this figure is drawn can not be identified with any of the figures given by Mat- thew [1902b, Pl. XVII, figs. 3a-e]. BorsrorDIA PULCHRA Matthew (p. 607). Ficure 5. Exterior and side view of ventral valve. (See note following fig. 5 1.) 5a. Exterior of ventral valve, with reticulate surface ornamentation on young shell only. U.S. Nat. Mus Cat. No. 52047a. 5b. Exterior of ventral valve. U.S. Nat. Mus. Cat. No. 52047b. 5c. Exterior and side view of dorsal valve. (See note following fig. 51.) 5d. Exterior of dorsal valve. U.S. Nat. Mus. Cat. No. 52047c. 5e. Exterior of ventral valve. U.S. Nat. Mus. Cat. No. 52047d. 5f and 5f. Top and back views of a ventral valve. U.S. Nat. Mus. Cat. No. 52047e. 5g. Cast of the interior of a ventral valve. U.S. Nat. Mus. Cat. No. 52047f. 5h and 5j. Casts of the interior of dorsal valves. U.S. Nat. Mus. Cat. Nos. 52047g and 52047h, respectively. 5k. Portion of surface, greatly enlarged, of the specimen represented by figure 51. U.S. Nat. Mus. Cat. No. 520471. 51. Exterior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52047i. The specimens represented are all from Locality 2y, Middle Cambrian sandstone on Catons Island, Long Reach, St. John River, New Brunswick, with the possible exception of the specimens represented by figures 5 and 5c, which can not now be located in the collections of the United States National Museum. These figures may have been drawn from specimens loaned to the Museum and since returned. 62667°—vou 51, pr 2—12——_14 4 (ha Ss pe Sg Se a PR AP bait gta tt he . bay ig Ge: Bart pera amet: fs Boll tin} 8 i r % Pe ii) 7 ee etd j sata MO aT te ; at? ‘ene e% isnor a és brea Comehar oe elas Fauna Eye esa eae CPi As ex. PLATE LXIII. cl. Cardinal scars. j. Anterior lateral muscle scar. f. Flexure line of area. k. Middle lateral muscle scar. F’. Cast of foraminal tube. 1. Outside lateral muscle scar. p. Pedicle furrow. s. Median septum. h. Central muscle scar. i. Transmedian muscle scar. ACROTHELE CERATOPYGARUM (Brégger) (p. 640). Ficures 1 and la. Top and side views of a ventral valve, the type specimen, from Locality 323h, passage beds between the Upper Cambrian and the Ordovician, Ceratopyge limestone at Vestiossen, 10 miles south- southwest of Christiania, Norway. Copied from Brégger’s figures [1882, Pl. X, figs. la and 1b] of Discina (Acrotreta ?) ceratopygarum. 1b and 1c. Top and side views of an exfoliated ventral valve associated with the valve represented by figures land ila. U.S. Nat. Mus..Cat. No. 51977a. ACROTHELE BORGHOLMENSIS Walcott (p. 639). Ficures 2 and 2a. Top and side views of a partly exfoliated ventral valve, the type specimen, from Locality 310d, Upper Cambrian Ceratopyge slate at Borgholm, Oeland Island, Sweden. U.S. Nat. Mus. Cat. No. 51974a. Copied from Walcott [1908d, Pl. VIII, figs. 12 and 127]. 2b. Interior of a small dorsal valve associated with the specimen represented by figures 2 and 2a. U.S. Nat. Mus. Cat. No. 51974b. ACROTHELE? MINUTA Walcott (p. 650). Figure 3. Exterior view of a partly exfoliated dorsal valve, the type specimen, from Locality C6, Middle Cambrian shaly limestone 2.5 miles southwest of Yenchuang, Sintai district, Shantung, China. U.S. Nat. Mus. Cat. No. 52519a. ACROTHELE RARA Walcott (p. 655). Ficure 4. Cast of interior of a ventral valve, the type specimen, from Locality €57, Middle Cambrian shale 3 miles south of Kaokiapu, Sintai district, Shantung, China. U.S8. Nat. Mus. Cat. No. 52518a. 4a. Cast of interior of a dorsal valve associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 52518b. AOROTHELE sp. undt. @ Walcott (p. 662). Ficure 5. Top and side view of type specimen from Locality 319b, Lower Cambrian limestone at St. Simon, Quebec, Canada. U.S. Nat. Mus. Cat. No. 52032a. ACROTHELE COLLENI Walcott (p. 640). [Text figs. 554-E, p. 641.] Figures 6 and 6’. Top and side views of the type specimen, a ventral valve, from Locality 4q, Middle Cambrian shale near Gordon Mountain, Ovando quadrangle, Montana. U.S. Nat. Mus. Cat. No. 51978a. 6a and 6a’. Top and back views of the posterior portion of a ventral valve associated with the shell repre- sented by figure 6. U.S. Nat. Mus. Cat. No. 51973b. 6b. Exterior of dorsal valve associated with the shell represented by figure 6. U.S. Nat. Mus. Cat. No. 51973c. 212 Va U. S. GEOLOGICAL SURVEY 10° FRANCES WIESER DEL. 10° lo HELIOTYPE CO SOSTO MONOGRAPH LI PL. LXiII PLATE LXIII. Adit} JTIELMERSENIA LADOGENSIS (Jeremejew) (p. 368). Fieure 7, Exterior view and side outline of a ventral valve from Locality 336p, Upper Cambrian sandstone at Kunitz, Pskow, Russia. U.S. Nat. Mus. Cat. No. 51941a. 7a. Exterior of a transverse dorsal valve from Locality 3360, Upper Cambrian sandstone at Koporje, St. Peters- burg, Russia. U.S. Nat. Mus. Cat. No. 51940a. 7b and 7b’. Exterior of a rounded ventral valve, and side outline, associated with the specimen represented by figure 7a. U.S. Nat. Mus. Cat. No. 51940b. 7c. Posterior view of a dorsal valve from Locality 336g, Upper Cambrian sandstone near Ladoga, Government of St. Petersburg, Russia. Copied from Pander [1861, Pl. IT, fig. 2f] 7d. Interior view of a ventral valve, the type specimen, associated with the valve represented by figure 7c. Copied from Pander [1861, Pl. II, fig. 2d]. 7e. Exterior of a dorsal? valve associated with the specimen represented by figure 7a. U.S. Nat. Mus. Cat. No. 51940c. 7f. Interior of a ventral ? valve associated with the specimen represented by figure 7a. U.S. Nat. Mus. Cat. No. 51940d. Osotts (WeEsTONIA) ELONGATUS Walcott (p. 459). Figure 8. Compressed, exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 51722b. 8a. Exfoliated interior of a ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 51722a. Copied from Walcott [1908d, Pl. VII, fig. 12]. 8b and 8c. Exfoliated interiors of dorsal valves. U.S. Nat. Mus. Cat. Nos. 51722c and 51722d, respectively. 8d. Enlargement of a portion of the matrix of the outer surface of the dorsal valve represented by figure 8b. The spaces inclosed by the oblique lines are not so convex as represented on the figure. U.S. Nat. Mus. Cat. No. 51722c. The specimens represented are all from Locality 105x, Middle Ordovician shales in Wasatch Canyon, north ‘of Brigham, Boxelder County, Utah. OxsoLus (WesTonIA) NoTcHENSIS Walcott (p. 463). Ficure 9. Fragment of a ventral valve, the type specimen, preserving a portion of the outer surface, from Locality 105t, Lower Ordovician limestone on Notch Peak, House Rangé, Utah. U.S. Nat. Mus. Cat. No. 5173la. Copied from Walcott [1908d, Pl. VII, fig. 13]. OxsoLus (ForprinrA) PERFECTUS Walcott (p. 429). Ficures 10 and 10’. Exterior and side view of a ventral valve. U.S. Nat. Mus. Cat. No. 51947b. 10a. Interior of a ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 51947a. Copied from Walcott [1908d, Pl. Vil, fig. 16]. 10b. Exterior and side view of a dorsal valve. U.S. Nat. Mus. Cat. No. 51947c. 10c and 10d. Interiors of dorsal valves. U.8..Nat. Mus. Cat. Nos. 51947d and 51947e, respectively. The specimens represented are all from Locality 30n, Middle Cambrian Weeks limestone, in Weeks Canyon, House Range, Utah. aN ACY Codey Fy! ih a ahi aa ; : ai Nevoeiad i : ere es pan nr ae re Te ees te tae ae Tee é' De AN | i ; Paar . ie he We Hi bi f ahi aay nt parce a aed ; ss Ab on ¥ 5 ae avec ae en ere i ae Pa ah we Shed dit et a ih | ee ie ve - BLADE iocan 215 PLATE LXIV. a. Outer lateral space of area. h. Central scars. cl. Cardinal scars. s. Median septum or ridge. {. Flexure line of area. y. Visceral area. fa. False area. vs. Main vascular sinus. p. False pedicle groove. x’’. Cast of apical callosity. ACROTRETA ATTENUATA Meek (p. 675). [Pl. LXXIX, figs. 6 and 6a.] Fieures 1, 1’, 1’, and la, la’, la’’. Top views with side and back views of ventral valves in the material upon which Meek founded the species. From Locality 302, Middle Cambrian limestone east of West Gallatin (Gallatin) River, above Gallatin, Montana. U.S. Nat. Mus. Cat. Nos. 7867a and 7867b, respectively. Figure 1 represents the type specimen. ; ; lb, 1b’, 1b’, and Ic, le’, 1c’. Top, side, and back views of two ventral valves from Locality 156a, Middle Cambrian limestones north of East Gallatin River, near Hillsdale, Montana. U.S. Nat. Mus. Cat. Nos. 52063a and 52063b, respectively. 1d, 1d’, 1d’’; le, le’, le’; and 1f, 1f’, 1f/”. Top, side, and back views of three ventral valves, from Locality 4n, Middle Cambrian limestone in the divide at the head of Jackson Creek, Teton Mountains, Wyoming. U.S. Nat. Mus. Cat. Nos. 52067a, 52067b, and 52067c, respectively. lg, lg’, and 1g”. Top, side, and back views of a ventral valve from Locality 159, Middle Cambrian limestone on the north side of West Gallatin (Gallatin) River, Montana. U.S. Nat. Mus. Cat. No. 52064a. Ih. Dorsal valve associated with the ventral valves represented by figures 1 and la. U.S. Nat. Mus. Cat. No. 7867c. li. Interior of ventral valve, showing base of apical callosity, vascular sinuses, and cardinal scars. From p Locality 10y, Middle Cambrian Marjum limestone, southeast of Marjum Pass, House Range, Utah. U.S. Nat. Mus. Cat. No. 52070a. 1j, 1k, and 11. Top, back, and side views of a cast of the interior of a ventral valve associated with the shell represented by figure li. U.S. Nat. Mus. Cat. No. 52070b. 1m. Interior of a dorsal valve associated with the specimen represented by figure li. U.S. Nat. Mus. Cat. No. 52070ce. In. Interior of a dorsal valve from Locality 3s, Middle Cambrian shales of the Wheeler formation, east of Ante- lope Springs, House Range, Utah. U.S. Nat. Mus. Cat. No. 52069a. lo. Exterior of a dorsal valve associated with the specimen represented by figure In. U.S. Nat. Mus. Cat. No. 52069b. : ACROTRETA DEFINITA Walcott (p. 683). FicurEs 2, 2’, 2’; 2a, 2a’, 2a/’; and 2b, 2b’, 2b’. Top, side, and back views of typical forms of the ventral valve. U.S. Nat. Mus. Cat. Nos. 35270a, 35270b, and 35270c, respectively. 2c, 2c’, and 2c’”. Cast of the interior of a ventral valve, the type specimen, with back and side views. U.S. Nat. Mus. Cat. No. 35270d. 2d, 2d’, and 2d’’. Top, back, and side views of the cast of the interior of a dorsal valve, showing the area, cardinal scar, etc., with unusual clearness. U.S. Nat. Mus. Cat. No. 35270e. 2e, 2i, and 2g. Exterior views of three dorsal valves, illustrating variation in outline. U.S. Nat. Mus. Cat. Nos. 35270, 35270g, and 35270h, respectively. . The specimens represented by figures 2, 2a-g are from Locality 163, Middle Cambrian Spence shale member of Ute limestone, Spence Gulch, 15 miles west of Montpelier, Idaho. FiaurEs 3, 3a, and 3b. Top, back, and side views of a cast of a ventral valve from Locality 55, Middle Cambrian Eldorado limestone in New York Canyon, Eureka district, Nevada. U. S. Nat. Mus. Cat. No. 35271a. 216 | U. S. GEOLOGICAL SURVEY ] jf FRANCES WIESER DEL. MONOGRAPH LI PL. LXIV | eon en y an Mur hove Sire IEA Lacy PLATE LXV. a. Area. h. Central scars. a’. Outer lateral space of area. s. Median septum or ridge. el. Cardinal scars. vs. Main vascular sinus. fa. False area. x’. Cast of apical callosity. fp. False pedicle groove. ACROTRETA IDAHOENSIS Walcott (p. 687). [Pl. LXVIII, figs. 2, 2a-g.] Ficures 1, l’, 1’; la, la’, la’’; 1b, 1b’, 1b”; and 1c, le’, le’. Top. side, and back views of typical forms of the ventral valve. U.S. Nat. Mus. Cat. Nos. 52091a, 52091b, 52091c, and 52091d, respectively. Figure 1b repre- sents the type specimen. 1d, 1d’, and 1d”. Top, back, and side views of cast of the interior of a ventral valve. U.S. Nat. Mus. Cat. No. 52091e. le. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52091f. li. Interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52091g. ; lg. Natural cast of the interior of the dorsal valve represented by figure 1f. U.S. Nat. Mus. Cat. No. 52091g. Jhand li. Exteriors of two dorsal valves. U.S. Nat. Mus. Cat. Nos. 52091h and 52091i, respectively. The specimens represented are all from Locality 5¢, Upper Cambrian limestone in Twomile Canyon, 2 miles south- east of Malade, Idaho. ACROTRETA ATTENUATA var. Walcott (p. 676). Ficures 2, 2’, and 2’’. Top, side, and back views of a specimen with a more distinctly marked false area than usually occurs in typical A. attenuata. Associated with the type of that species in Locality 302, Middle Cam- brian limestone east of West Gallatin (Gallatin) River above Gallatin, Montana. U.S. Nat. Mus. Cat. No. 52071a. ACROTRETA KUTORGAI Walcott (p. 692). [Text fig. 58, p. 692.] Ficures 3, 3’, 3, and 3a, 3a’, 3a’’. Top, back, and side views of the exterior of two ventral valves from Locality 139a, Middle Cambrian limestone near Chepultepec, Jefferson County, Alabama. U.S. Nat. Mus. Cat. Nos. 58305a and 58305b. 3b, 3b’, 3b”, and 8c, 3c’, 3c’. Top, back, and side views of casts of the interior of ventral valves. U.S. Nat. Mus. Cat. Nos. 35277a and 35277b, respectively. Figure 3b represents the type specimen. 3d. Side view of cast of ventral valve, showing cast of pedicle tube. U.S. Nat. Mus. Cat. No. 35277c. 3e. Cast of pedicle tube, showing lines of shell growth. U.S. Nat. Mus. Cat. No. 35277d. 3g. View into cast of ventral valve, with cast of area of dorsal valve in position. U.S. Nat. Mus. Cat. No. 35277e. This specimen is tipped so as to show the cast of the areas of both the ventral and dorsal valves in text figure 58, page 692. 3h, 3i, 3j, and 3k. Casts of interiors of dorsal valves, illustrating variation in median ridge, muscle scars, etc. U.S. Nat. Mus. Cat. Nos. 352771, 35277g, 35277h, and 352771, respectively. The specimens represented by figures 3b-k are all from Locality 90x, Middle Cambrian siliceous nodules in the Conasauga shale, Coosa Valley, Cherokee County, Alabama. AcROTRETA RUDIS Walcott (p. 702). [Pl. LXV, fig. 1.] Ficure 3f. Ventral valve, the type specimen, flattened in the shale of Locality 101a, Middle Cambrian, 3.5 miles south- west of Rogersyille, Hawkins County, Tennessee. U.S. Nat. Mus. Cat. No. 52111a. Copied from Walcott [1908d, Pl. IX, fig. 5]. 218 U. S. GEOLOGICAL SURVEY FRANCES WIESER DEL. HELIOTYPE CO BOSTON MONOGRAPH L LXV i j f ie i Rye an i f ip " a 3. Copied from Hall and Clarke [1893b, Pl. LXII, fig. 9]. 6g. Oblique view of the specimen represented in figure 6f, showing the elevation of the spondylium and the length of its supporting median septum. Copied from Hall and Clarke [1893b, Pl. LXII, fig. 10]. Ss. The specimens represented are all from Locality 227, Ordovician limestone near Fort Cassin, Addison County, Vermont. r JedbvaIeJa. (CJUUL, 345 PLATE CIII. a’, Anterior adductor impressions. sp. Spondylium. a’’, Posterior adductor impressions. s. Median septum. r. Diductor scar. vs. Vascular sinus. HUENELLA TEXANA (Walcott) (p. 808). Ficure 1. Strongly costate ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 52494a. la. Ventral valve with well-defined costz in the mesial sinus, and nearly smooth cardinal slopes. U.S. Nat. Mus. Cat. No. 52494b. 1b. Ventral valve in which there are only slight traces of the radiating costee in the mesial sinus. U.S. Nat. Mus. Cat. No. 52494c. le. Ventral valve without radiating coste, with back outline. U.S. Nat. Mus. Cat. No. 52494d. 1d. Ventral valve, with side outline, from Locality 71, Upper Cambrian limestone in Cold Creek Canyon, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 52495a. le. Dorsal valve, with strong costee on the median fold and cardinal slopes. U.S. Nat. Mus. Cat. No. 52494e. 1f. Dorsal valve, with fine radiating coste. U.S. Nat. Mus. Cat. No. 52494f. lg. Dorsal valve, having median fold with well-marked costs and smooth cardinal slopes, with back outline of the same. U.S. Nat. Mus. Cat. No. 52494¢. lh. Oblique section of spondylium of ventral valve a short distance from the apex. U.S. Nat. Mus. Cat. No. 52494h. li. Section of dorsal valve cutting across the spondylinm. U.S. Nat. Mus. Cat. No. 524941. With the exception of figure 1d, all the specimens represented are from Locality 68, Upper Cambrian limestone, in Packsaddle Mountain, Llano County, Texas. HuENELLA aBnormis (Walcott) (p. 805). [Text fig. 13, p. 299.] A Fiaure 2. Ventral valve with strong radiating coste. U.S. Nat. Mus. Cat. No. 52462a. 2a and 2a’. Exterior and side views of ventral valve, the type specimen, with radiating cost in the mesial sinus. U.S. Nat. Mus. Cat. No. 52462b. 2b. Cast of interior of ventral valve, showing cast of spondylium, main vascular canals, and muscle scars. U.S. Nat. Mus. Cat. No. 52462c. 2c. Dorsal valve with prominent median fold, from Locality 158, Upper Cambrian limestone north of East Gallatin River, near Hillsdale, Threeforks quadrangle (U. 8. Geol. Survey), Gallatin County, Mon- tana. U.S. Nat. Mus. Cat. No. 52461a. 2d and 2d’. Top and side view of nearly smooth dorsal valve. U.S. Nat. Mus. Cat. No. 52462d. 2e. Dorsal valve with several plications on median fold. U.S. Nat. Mus. Cat. No. 52462e. 2f. Interior of dorsal valve showing muscle scars and vascular markings. U.S. Nat. Mus. Cat. No. 52462f. 2e. Posterior view of a ventral valve showing area. U.S. Nat. Mus. Cat. No. 52462g. 2h. Partial cast of interior of dorsal valve. U.S. Nat. Mus. Cat. No. 52462h. 2i. Interior of a dorsal valve in which the muscle scars and spondylium (cruralium) have been more or less eroded. U.S. Nat. Mus. Cat. No. 524621. 2}. Cast of the interior of a dorsal valve, showing strong muscle scars and radiating costz on the mesial fold. This specimen is associated with the shell represented by figure 2c. U.S. Nat. Mus. Cat. No. 52461b. 2k. Cast of the interior of a dorsal valve, showing radiating vascular canals at the top of the cast of four strong costee. This specimen is associated with the shell represented by figure 2c. U.S. Nat. Mus. Cat. No. 52461c. 21 and 2m. Sections of ventral and dorsal valves cut across the umbo to show sections of the spondylium in each valve. U.S. Nat. Mus. Cat. Nos. 52462] and 52462k, respectively. With the exception of figures 2c, 2j, and 2k, the specimens represented by figures 2, 2a—m are from Locality 4j, Middle Cambrian limestone at the head of Deep Creek, Canyon quadrangle (U. 8. Geol. Survey), Yellowstone National Park, Wyoming. 346 U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. Cll! FRANCES WIESER DEL. PLATE CIII. d47 SyntTRopHia ALATA Walcott (p. 799). Figures 3, 3’, and 3”. Cast of the interior of a ventral valve, with side and back views. U.S. Nat. Mus. Cat. No. 52466a. 3a. Exterior of ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 52466b. 3b and 3c. Casts of interior of ventral valves. U.S. Nat. Mus. Cat. Nos. 52466c and 52466d, respectively. 3d. Partial cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 52466f. The specimens represented by figures 3, 3a-d are all from Locality 69, Upper Cambrian limestone near Honey Creek, Burnet County, Texas. SYNTROPHIA RoTUNDATA Walcott (p. 804). Fiaures 4, 4’; 4a; and 4b, 4b’. Top and side views of three dorsal valves varying in form and in strength of median fold. U.S. Nat. Mus. Cat. Nos. 524938a, 52493b, and 52493c, respectively. 4a’. View of area and hinge line of ventral valve. U.S. Nat. Mus. Cat. No. 52493h. 4c and 4c’. Top and side views of ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 52493d. Another specimen (Cat. No. 52493g) was used to restore certain portions of this figure. U.S. Nat. Mus. 4d. Section across the umbo of a ventral valve, showing outline of section of spondylium. Cat. No. 524938e. 4e. Section of shell and spondylium of dorsal valve. U.S. Nat. Mus. Cat. No. 52493f. The specimens represented by figures 4, 4a-e are all from Locality 14k, Upper Cambrian limestone on Wolf | Creek, 15 miles (24.2 km.) west-southwest of Sheridan, Bighorn Mountains, Wyoming. «| ee ACO IEN/ © 349 PLATE CIV. el. Area of attachment of posterior muscles. , uc. Umbonal cavity. h. Central scars. vs. Main vascular sinuses. sp. Cast of spondylium. SYNTROPHIA CALCIFERA (Billings) (p. 800). Ficure 1. Ventral valve,probably the one represented by figure 1c. Copied from Billings [1861a, fig. 3a, p. 319]. la. Dorsal valve, possibly the one represented by figure le. Copied from Billings [1861a, fig. 3b, p. 319]. 1b. Cast of a ventral valve showing spondylium. Copied from Billings [1861a, fig. 3c, p. 319]. le and lc’. Top and side views of ventral valve, from Locality 392j, Lower Ordovician limestone at Point Levis, Province of Quebec, Canada. Geol.Survey Canada. In all probability this is the specimen used by Billings in drawing his figure 3a [1861la, p. 319]. It may be taken as the type. 1d. Ventral valve with gently rounded shallow sinus, with a large projection to fitin the fold of the dorsal valve. It is associated with the specimen represented by figure 1c. Geol. Survey Canada. le and le’. Top and side views of a dorsal valve from Locality 392i, Lower Ordovician limestones at Phillipsburg, Province of Quebec. Geol. Survey Canada. The specimen represented by figure le is possibly the one used by Billings in drawing his figure 3b [186la, p. 319]. lf. Ventral valve with side outline. U.S. Nat. Mus. Cat. No. 52476a. lg and lh. Top and side view of a ventral valve. U.S. Nat. Mus. Cat. No. 52476b. li. A smooth dorsal valve, doubtfully referred to this species. U.S. Nat. Mus. Cat. No. 52476c. The specimens represented by figures 1f-i are from Locality 392j, Lower Ordovician limestones at Point Levis, Province of Quebec, Canada. “ CLARKELLA MONTANENSIS (Walcott) (p. 810). Fieures 2 and 2’. Top and back view of a broken ventral valve. U.S. Nat. Mus. Cat. No. 11587a. 2a and 2a’. Top and side view of a rhomboidal dorsal valve, the type specimen. U.S. Nat. Mus. Cat. No. 11587b. 2b. Transverse dorsal valve. U.S. Nat. Mus. Cat. No. 11587c. 2c and 2d. Sections across the umbo of two ventral valves, showing sections of the septa supporting the spondylium. U.S. Nat. Mus. Cat. Nos. 11587d and 11587e, respectively. The specimens represented are all from Locality 302}, Ordovician limestone east of West Gallatin (Gallatin) River, above Gallatin, Gallatin County, Montana. HUENELLA ORIENTALIS (Walcott) (p. 808). Ficure 3. Top and side views of a ventral valve, the type specimen. U.S. Nat. Mus. Cat. No. 52564a. 3a. Top and side views of an exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 52564b. 3b. Partly exfoliated dorsal valve. U.S. Nat. Mus. Cat. No. 52564c. ~ The specimens represented are all from Locality C64, Upper Cambrian limestone 2.7 miles (4.4 km.) southwest of Yenchuang, Sintai district, Shantung, China. SYNTROPHIA ORTHIA Walcott (p. 803). Ficure 4. Ventral valve, the type specimen, from Locality C56, Upper Cambrian Chaumitien limestone at Pagoda Hill, 1 mile (1.6 km.) west of Tsinan, Shantung, China. U.S. Nat. Mus. Cat. No. 52562a, 4a and 4a’. Exterior of ventral valve, with side outline, from Locality €64, Upper Cambrian limestone 2.7 miles (4.4 km.) southwest of Yenchuang, Sintai district, Shantung, China. U. 8S. Nat. Mus. Cat. No. 52563a. 4b ana 4b’. Top and side views of a dorsal valve from Locality €54, Upper Cambrian Chaumitien limestone 0.66 mile (1.1 km.) west of Tsinan, Shantung, China. U.S. Nat. Mus. Cat. No. 52561a. SWANTONIA ANTIQUATA (Billings) (p. 797). Fictres 5, 5a, and 5b. Top, side, and back views of the cast of a ventral valve from Locality 319e, Lower Cambrian sandy shales about 2 miles (3.2 km.) east of Swanton, Franklin County, Vermont. U.S. Nat. Mus. Cat. No. 15363a. This specimen was figured by Walcott [1886b, Pl. VII, fig. 8] as Camarella antiquata. U. S. GEOLOGICAL SURVEY MONOGRAPH LI PL. CIV FRANCES WIESER DEL, HELIOTYPE CO. BOSTCK PLATE CIV. 351 SWANTONIA WEEKSI Walcott (p. 797). Figure 6. Top view of an imperfect ventral valve, the type specimen, from Locality 1v, Lower Cambrian shales of No. 3 of the Silver Peak group, 3 miles north of Valcalda Spring and 4 miles northwest of the Drink- water mine, Esmeralda County, Nevada. U.S. Nat. Mus. Cat. No. 52500a. QUEBECIA cIRCE (Billings) (p. 610). Figure 7. Cast of interior of ventral valve, showing outline of main vascular sinuses and cardinal muscle scars. U.S. Nat. Mus. Cat. No. 14892a. 7a and 7a’. Back and side views of specimen represented by figure 7. U.S. Nat. Mus. Cat. No. 14892a. 7b. Back view of the cast of a ventral valve, in which the cardinal scars are large and strongly defined. The specimen from which this figure was drawn can not be located. 7c. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 14892c. 7d. Artificial cast of the interior of a dorsal valve. The original specimen can not be located. U.S. Nat. Mus. Cat. No. 14892f. 7e. Artificial cast taken from the artificial cast shown by figure7d. U.S. Nat. Mus. Cat. No. 14892e. Specimen figured by Walcott [1886b, Pl. X, fig. 3a]. 7f. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 14892b. 7g. Cast of the interior of a dorsal valve which is old and thick shelled. U.S. Nat. Mus. Cat. No. 14892d. The specimens represented are all from Locality 3191, Lower Cambrian limestone bowlders in conglomerate at Trois Pistoles, on St. Lawrence River below Quebec, Canada. at v t ; . INDEX TO PART II. Nore.—This index includes also reference to species figured in Part I (text figures), and all page references are to that part. In order to make the figured species easily accessible to one not familiar with the numerous changes in the generic references the entries are arranged alphabetically by genera, subgenera, species, and varieties. Roman numerals refer to plates, arabic numerals to the figures on the plates. The index to Part I includes the plate and figure reference of each of the type specimens figured in the monograph. Beeb C Reese HEC eceers LIX: 5, 5a-e. SERRE ACES aA HAAR aocanc LVIUII: 1, la-g. panderi Waicott... pretiosa (Billings). . prima) (Matthew, meee. so sees se setae LXI: 6, 6a-b; LXII: 2. prima costata (Matthew)............-..-.---- LXI: 4, 4a-d. primeva (de Verneuil and Barrande) .....-.. LVII: 6. proles!Matthewareeccoseccee saeacen ose ace ea LXII: 3, 3a-e; 4, 4a. quadrilineata Pompeckj......:-...-.-.-.----- LVII: 5. MATA Al COLL Ameer ee eee Rane eee eS LXIII: 4, 4a. spurri Walcott. -- LX: 3, 3a-c. SubsiduaryGWihite) terse eeeeere erect eee LX: 1, 1a-o; 8. subsidua hera, Walcott..................----- LX: 9. subsidua leevis Walcott...-......--........-- Not figured. HumneniawWalcouteeesee = eee eeeerice eee LX: 7, 7a. villaboimensis Delgado........-.....-.------- Not figured. WoodworthijwWalcotte ss. sseeeee see see aenee LX: 6. SVOLKCNSISAVial COUbssee see eeieree sael= sie cles nie LIX: 4, 4a-b. sp. undt. Moberg..- sp. undt. Walcott Acrothele (Redlichella) granulata (Linnarsson)..... LVI: 2, 2a-n. AMerothyraminor Walcotte-casess2- ses. oee =e LXXVI: 4, 4a-b; Text fig. 59, p. 717. proavia) (Matthew) =:--Ss22---------n---2-c- << LXV: 3; LXXVI: 3,3a-u. SeralMat thew) paar see ee eae lars eee eta LXXX: 4,4a-c; 5, 5a-d; 6,6a-i; 7, 7a-b; 8?. Spm aries Mia tile weyers eta lete lata se iaietelelalat=tele)= LXXX:1,1a-d. -LXXX:3,3a-b. - LXXX: 2, 2a-b. 23 signata orta Matthew. - signata prima Matthew 62667°—vot 51, pr 2—12 abnormis [Huenella], (Walcott)................... CIII: 2,2a-m; Acrotreta argenta Walcott..........--..----------- LXVII: 5, 5a-g. Text fig. 13, p. 299. attenuataiMealk:. 5 -o.-. mepneeres aceon LXIV: 1, 1a-o; acadicus [Obolus}], Walcott........................-2kI25. LXXIX: 6, 6a. (Acritis) antiquissimus [Obolus), (Eichwald)....... XIII: 3; attenuatalvar. Walcott-.2-22.2-22--..:------- LXV: 2. XV:2, 2a-d. babeliBarrandess.-.=: 00R BP XV: 2, 2a-d. apollinis [Obdlus], Eichwald.-............--.------- apollinis ingricus [Obolus], Eichwala.....-.-.-..- apollinis maximus [Obolus], Mickwitz....-..-...--- apollinis quenstedti [Obolus], (Mickwitz)......... appalachia [Billingsella?], Walcott.....--....---- appalachia [Dicellomus], Walcott.....-..-..----.-- argenta [Acrotreta], Walcott...........---..------- argenta [Nisusia (Jamesella)], Walcott. argia(Syntrophia primordialis], Walcott arguta [Lingulella], (Walcott).........---..--.----- artemis [Acrothele], Walcott. -......- asiatica [Obolella], Walcott........-- atava [Lingulella], (Matthew) atava [Eoorthis], (Matthew)..........-------------- atava insule [Lingulella], (Matthew)...........--.. atlantica [Obolella], Walcott. .......-...--..------- atrypoides [Orusia lenticularis], (Matthew). - -.-.- attenuata [Acrotreta], Meek..........-..-.---.----- attenuata var. [Acrotreta], Walcott.........-..---- auga [Lingulella], (Walcott)...........----.--..---- aurora [Obolus (Westonia)], (Hall)..........-....-- VII: 1-8, 10-17; XIV: 6, 6a; Text figs. 4 and 15, p. 299. Not figured. VII: 9; XIV: 7, 7a. Text figs. 34A-B, p. 374. LXXXVII: 2, 2a-b. LIII: 4, 4a-g. LXVII: 5, 5a-g. .-CI: 9, 9a-b. CIT: 3. XXIV: 5, 5a-b. .- Text fig. 54, p. 634. --LV: 6, 6a. ..XXXV: 5,5a-h. XCV:7, 7a-b. XXXV: 8, 8a. LV:1a-i; Text fig. 51, p. 590. XCVIII: 5. LXIV: 1,1a-0; LXXIX: 6, 6a. XXIV: 6, 6a-g. XLVI:1, la-h. avia [Acrothele], Matthew-...-.... pe rennoacacecasoe LXI: 7, 7a-b; LX: 1, 1a-k. avia puteis [Acrothele], Matthew........-...------- Not figured. babel [Acrotreta], Barrande -LX XVII: 6, 6a-b. baileyi [Acrotretd], Matthew............----.------ LXXVII:2, 2a-d. balticus [Obolus (Westonia)], Walcott.........--. XLVIII:7, 7a-b. barabuensis [Syntrophia], (A. Winchell) - .--CII: 1, la-g. ? barrandei [Botsfordia], Walcott ---- .--LVII: 7, 7a-b. bavarica [Eoorthis], (Barrande). -.- ..-XCVII: 4. bavaricus [Obolus?], (Barrande) XV: 10, 10a. bella [Lingulella], (Walcott)...............-- hasates XIX: 2, 2a-q; XXXVI: 4. bella [Micromitra (Paterina)], (Billings)....... ...II: 1,la-c. bellapunctata [Acrothele], Walcott.........-------- LVII: 3, 3a-b. bellatula [Acrotreta], Walcott. -.... .-- LX XVIII: 4, 4a-d. belli [Obolus], (Billings)...........--..- -X XXVIII: 3, 3a-b. bellula [Acrothele], Walcott... ...-- - LVIII: 5, 5a-h. bellula [Lingulella], (Walcott)......-..----.-------- XIX: 1, 1a-e. bellulus [Obolus (Fordinia)], (Walcott).......-... LI: 3, 3a-f. belti [Acrotreta], (Davidson) bergeroni [Acrothele], Walcott... Bicia}gemma) (Billings) t3. eee aeons seeea eer eee whiteavesi Walcott........ Billingsella? appalachia Walcott... LXXXVII: 2, 2a-b. DbivaasWialcotteste so. peta cee ee eco ecie oe eee Text figs. 65A-C, p. 750. coloradoensis (Shumard).............-.-.---- LXXXV:1, 1la-z; Text figs. 5, p. 299, and 66, p. 751. dice)Walcotts22-:--------- .--CI: 8, 8a-d. exporrecta (Linnarsson)........-- ---LXXXVIII:1, 1a-l. exporrecta rugosicostata Walcott.....-..--- LXXXVIII: 2, 2a-c. hicksi (Salter MS.) (Davidson)-.-.---.---.--- XCVII: 7, 7a-b. highlandensis (Walcott) .--LXXXVII: 4, 4a-c. lindstrémi (Linnarsson).........-..-.-.------- LXXXVII: 6, 6a-f. majoniWealcottsetce: 2 teseeor esse tame ee en LXXXVI; 1, la. IMIATIONMVW 21 CO blast ee = eee eee een Text figs. 67A-B, p. 758. obscura Walcott. -s-- ose ese eee seioe eae LXXXVI: 6. orientalis) @VWijhitfield) sess] eeeee ee eee LXXXVI: 2, 2a-b. plichtella \Wialcotts-+--+---ss---s-sesnee cere LXXXVI: 3, 3a-n; Text fig. 1, p. 299. pumpellyiiwWialcottzs+----ee-s sesso eres eee XCVII: 8, 8a-c. retroflexa|(Matthew)e--2s-s-n--e-eaeee see XC: 1, la-h. richthofeni Walcott... Tomingeri! (Barrande)Sessss eee eee XC: 2, 2a-n. salemensis ((Wialcott) 25-52 2222-----2-s---e eee LXXXVII: 3, 3a. StriatasWialcottssce--=- seen eee eeee LXXXVI: 4, 4a-c. whitfieldil(Walcoth):sse) ses esse eee eee LXXXVI: 5, 5a. billingsi [Huenella], (Walcott).....-.....--.-------- CII: 5, 5a-c. billingsi [Protorthis], (Hartt).......-- ..---XCIX: 1, la-g. billingsiana (Lingulella], (Whiteaves). Bee no-2- OD. GEEREY bisecta [Acrotreta], Matthew -..-.........---------- XLVI: 7, 7a-e. bivia [Billingsella], Walcott....-...........-.------- Text figs. 65A-C, p. 750. blackwelderi [Obolus (Westonia)] Walcott-......... XX XIX: 10; 10a-c. bohemica [Acrothele], (Barrande).-.........-..---.- LVII: 1, 1la-d. borgholmensis [Acrothele], Walcott..........--..-.- LXIII: 2, 2a-b. bornemanni [Lingulella], (Walcott).. XXX: 18, 18a-c. Botsfordia? barrandei Walcott.-......-..-..-.---.-. LVII: 7, 7a-b. (ceelatay (Ela) Seca es se eriemt eee ee ener LIX:1,1a-q;3,3a-b. granulata (Redlich) LVII: 4, 4a-r. pulchra (Matthew)......-.-. LXII: 5, 5a-1. bottnicus [Obolus (Westonia)], (Wiman) .....-...- XLVIII: 4, 4a-c. bretonensis [Obolus (Palzeobolus)], (Matthew) ----- XXXII: 5, 5a-g. bretonensis lens [Obolus (Paleeobolus)], (Matthew). Not figured. (Broggeria) salteri [Obolus], (Holl)........-..---.-.- XIII: 1, la-n; XV: 4, 4a-d. buchi [Keyserlingia], (de Verneuil).............---- LXXXI: 4, da-e. buttsi [Lingulella], Walcott cewlata [Botsfordia], (Hall)...............-.-..------ LIX: 1, la-q; 3, 3a-b. calcifera [Syntrophia], (Billings)... .. ae eee CIV: 1, la-i. cambria [Schuchertina], Walcott.......-..-..------- LI: 6, 6a-m. cambria [Syntrophia], Walcott.................--.-.Text figs. 72A—D, p. 800. campbelli [Syntrophia], Walcott............----..-- Text figs. 73A-F, p. 801. cancellata [Acrotreta??], Walcott............------- LXXIX: 5, 5a. cania [Lingulella], (Walcott).............-...------- XXXV: 3, 3a-d. INDEX. 50D carinata [Acrotreta], (Segerberg MS.) Moberg and Dicellomus nanus (Meek and Hayden)............- LIII: 1, la-l; 2, 2a, Seperberg: ents cscscensscss oom tocincscse Text figs. 56A-D, 3, 3a-d. p. 680. Danvusi Walcott, steesessesncenseeasscsaeeee LXXXIX:11,lla-d. cedens [Lingulella], (Barrande)................--..- XXX: 8. pectenoides (Whitfield)....................-. LIT: 6, 6a-c; celatus [Obolus (Schmidtia)], (Volborth)........... XIV: 1, la-c. Text figs. 48A-B, ceratopygarum [Acrothele], (Brogger)...............L-XIII: 1, la-c. p. 575. chinensis [Obolus], (Walcott).......... -- XX XIX: 7, 7a-b. pats | (Hall) coma. cae secs eee eee eee LII: 1, la-k; 2, 2a-i; christianiz [Eoorthis], (Kjerulf)...................- XCV: 1, la-h. 3; 4, 4a; 5, 5a-b; chromatica [Obolella], Billings...............2.....- LIV: 1, la-i. Text figs. 16A-B, chuarensis [Obolus (Westonia)], (Walcott). . -XXV: 2, 2a-e. p. 314, and 49A-B, cingulata [Kutorgina], (Billings) .......... --V: 1, 1a-s; p. 576. Text figs. 3 and 8, prolificus Walcott ............-..-2...22...-- LXXXIX:10,10a-b. p. 299,and 50A-C, SDHUNCt AV alCOLbes sss ce eee eee eee eee LII: 7, 7a. p. 581. dichotoma [ Acrothele], Walcott LX: 2. circe [Quebecia], (Billings)...............-.--..-.-- CIV: 7, 7a-g. Discinolepis granulata Waagen.. LXXXI: 3,3a-b. circularis [Acrotreta], Moberg and Segerberg........ Text figs. 57A-C, | Discinopsis gulielmi (Matthew)...-........-....-.. LXXXII: 5, 5a-c. Pp. 680. MSUICAEUISIV alCOLts --- sae eeneee ees ame e eee LXXXII: 6. clarkei [Lingulella), Walcott..............-.----..- Text figs. 42A-D, | discoideus [Obolus], (Halland Whitfield)..........XVIII: 6, 6a-d. p. 486. dolatus [Obolus], (Sardeson) .............-...---.- Text figs. 35A-B, Clarkella montanensis (Walcott) ...........-..---.- CIV: 2; 2a-d. p- 390. clarki [Dearbornia], Walcott...-..........----....-UX XXII: 7, 7a-d. doris [Eoorthis], (Walcott) ..................--.--- XCVII: 13, 13a. claytoni [Acrotreta)], Walcott.........-.......:.--. LXXIV: 3, 3a-b. dubia [Lingulella], (Walcott) ...................... XXIV: 4, 4a. colleni [Acrothele], Walcott.......................- LXIII: 6, 6a-b; dubia [Siphonotreta], Walcott ........-..... ---LXXXI; 7, 7a-b. Text figs. 55A-E, p. | dugaldensis [Protorthis (Loperia)], Walcott. -XCIX: 5, 5a-j. : 641. edsoni [Rustella], Walcott .................. ---I: 1,la-e. collicia [Lingulella], (Matthew)-.............-..-..- XXXV: 1, la-f; 2, | eggegrundensis [Acrotreta], Wiman...............- LXX: 2a-d. : 2a-d. eichwaldi [ Obolus], Mickwitz Not figured. coloradoensis [Billingsella], (Shumard)............. LXXXV: 1, la-z; elegans [Obolus], Mickwitz ..............--.------- XV: 3. Text figs. 5, p. 299, | elegantula [Curticia], Walcott ..........-.........- I: 2, 2a-1. and 66, p. 751. elegantula [ Eostrophomena], (Walcott).........-.- XCV: 6, 6a-b. columbiana [Philhedra], (Walcott).............-... LXXXI: 10. Elkania ambigua (Walcott) LI: 2, 2a-c. XII: 3, 3a; 8, Sa. --XOVII: 14. LXXVII: 1, la-b. complexus [Obolus], Barrande.......... compta [Nisusia], (Tate).............----- concentrica [Acrotreta], Walcott concinna [Lingulella], Matthew....................X XXIII: 2, 2a-h; XXXIV: 1, la-r. contraria [Orbiculoidea], (Barrande)............... LXXXI: 9. conula [Acrotreta], Walcott............-..---....- LXXV: 2, 2a-b. convexa [Acrotreta], Walcott convexa [Lingulella winona], (Walcott)... coriacea [Acrothele], Linnarsson............ LXVI: 6, 6a-c. --- XVIII: 4, 4a-d. .- LVI: 1, la-i. corrugata [Finkelnburgia osceola], (Walcott). ...... Not figured. costata [Acrothele prima], (Matthew).............- LXI: 4, 4a-d. crassa) [Obolella];\(Hall) see 0 22220 2 eo LIV: 2, 2a-n; Text fig. 14, p. 299. crassa elongata [Obolella], Walcott..............-.. LV: 5, 5a. crassus [Obolus (Schmidtia)], Mickwitz............XIV: 4, 4a-d. crenistria [Micromitra (Paterina)], (Walcott) ....... III: 4, 4a-b. cuneola [Lingulella], (Whitfield).............. XXVIII: 7, 7a-b. Curticia elegantula Walcott.....................--- I: 2, 2a-1. curvata [Acrotreta], Walcott............-..-......- LXVIII: 1, 1a-n. cyane [Obolus], (Billings)...................22-..2. XXVIII: 4, 4a-b. Dalmanella multisecta (Meek) parva (de Verneuil)............... -.-Text fig. 9, p. 299. - Text fig. 10, p. 299. subequatal (Conrad) s2es2 cesses se-ceec ee 2 Text fig. 2, p. 299. damesi [Lingulella], (Walcott) .............--.--.-. XXXIX: 8, 8a-c. dartoni [Obolus (Westonia)], Walcott............-. Text figs. 40A-C, p. 455. daunus [Eoorthis], (Walcott)........-........--..- XCV: 2, 2a-c. davidsoni [Lingulella], (Barrande).................X XXII: 1, la-e. davisi [Lingulella], (McCoy)........-...-...---.-.. SOXEX: 2, 2a; XXXI: 6, 6a-h. Dearbornia clarki Walcott............-...-----.--- LXXXII: 7, 7a-d. decipiens [Acrothele], Walcott..................--- LVIII: 3, 3a-d. decipiens [Obolus meconnelli], Walcott... -X XIII: 4, 4a-b. definita [Acrotreta], Walcott............-...--..--- LXIV: 2, 2a-g; 3, 3a-b. Delgadella lusitanica (Delgado).........-..-------- XXIX: 5, 5a-b. delgadoi [Lingulella], Walcott...........-...--..--- XXIX: 6, 6a-c. depressa [Acrotreta], (Walcott) .........-- descendens [Acrotreta ophirensis], Walcott. - XLVI: 8, 8a-c. --LXXVIII: 1, 1la-c. desiderata [Elkania], (Billings)..........-- -LI: 1, la-d. desiderata [Lingulella], (Walcott)..............-..- XX: 4, 4a-c; 5, 5a-j. desmopleura [Eoorthis], (Meek)....................XCVI: 1, la-r. desmopleura nympha [Eoorthis], Walcott. XCVI: 2. diablo [Eoorthis?], (Walcott) .............---.-----X CII: 3. dice [Billingsella], WIG Es cas Gane aacRBaaoanGaedane CI: 8, 8a-d. Dicellomus appalachia Walcott.............-..-.-- LIII: 4, 4a-g. desiderata (Billings) . LI: 1, 1a-d. day (Billings) |<< c seem seee eee ee XXX: 20, 20a; LI: 4, 4a-c. ella [Obolus (Westonia)], (Halland Whitfield) .....X XXIII: 3,3a-c; XLVII: 1, 1a-p. ella onaquiensis [Obolus (Westonia)], Walcott.....X LIX: 6, 6a. ellsi [Lingulella], (Walcott) ............-.:......-- XIX: 3,3a-c. elongata [Obolella crassa], Walcott ...............- LV: 5, 5a. elongatus [Obolus (Westonia)], Walcott .........-. LXIII; 8,8a-d. emmonsi [Acrotreta], Walcott ..........-....... .-- LXV: 6. endlichi [Micromitra sculptilis], Walcott..........- Text fig. 22, p. 342, Eoorthis agreste (Walcott)....-....-..-.. BatacSssae LXXXIX: 6, 6a. atavay (Matthew) = o2-cssceeneemscoesnee anes XCV: 7, 7a-b. bavarica (Barrande) . Bee cise = aE OAL a a christianize (Kjerulf) . daunus (Walcott)...... Sea Se XCV: 1, la-h. pabinsocacoccaGeces AONB ero Ee desmopleura (Meek)-..........-.------------ CVI: 1, la-r, desmopleura nympha (Walcott)..............XCVI: 2. *diablo|@Walcott) oc. 2es- sess 2-- 2 ase se OlMngs ‘doris|@Wialcott) =e eesmeee heen e eee eee XCVII: 13, 13a. Gaaoanecesceca XCIV: 3,3a-c. iddingsi (Walcott)... -XCI: 3,3a-b. indianola (Walcott) -.- -XCIV: 1t, 2, 2a-h. johannensis (Matthew). ....................-XCVII: 10, 10a. kayseri (Walcott)................----..----..- XCVII: 6,6a-b. | kichouensis (Walcott)...........-.----------- LXXXIX: 5. hastingsensis (Walcott) linnarssoni(@kaysen)maaaceeeeeeseeocisen eee XCVII: 5, 5a. Zi Mew berrysaWialcOthsse see -ema ean eiee eae Text figs. 69A-D, p. 783. newtonensis (Weller).........---------------- XCVII: 9, 9a. pagoda (Walcott)... papias (Walcott) primordialis (de Verneuil and Barrande) ..... XCVII: 1, la-d. remnicha) @Wanchell) sei asceeneese eee eee XCI: 1, la-s; XCII: 2, 2a-d; 3, 3a-e; Text fig. 7, p. 299. remnicha sulcata (Walcott)...-.......-..-.--XCII: 1, la-c. remnicha texana (Walcott)............-.----- XCII: 4, 4a-g. remnicha winfieldensis (Walcott)........---- XCI: 2, 2a-e. Saltensis| (KAYSCL) sane sence eee semen cee ae CALL lL tatei (Etheridge). SSO RSE SHE Se SHOE. CONAN Baby sbi thy onewwalcotttecss scores aaseeeee eens Text figs. 70A-C, p. 789. full bereil Walcott) seep areas KCV: 3. ‘wichitaensis|(Wialeott)<-.- 2-22-2222. 22-- XCIV: 1,1a-o,1u. wichitaensis leviusculus (Walcott)........... XCIV: Ip-s. 306 Eoorthis wimani (Walcott) ...............- qNCOnaS XCV: 4, 4a-d. Zeno Walc0tt:-.-----<--cc-cacccecessrteccsees exh figs, (LA—By p. 792. sp: undt. a (Pompeck))-..... 2... scccccncecce- Not figured. sp. undt. b (Pompeckj)........-------------- Not figured. Sp; UNG Cl(\WialCOtt) | ecnec cones cone acislena= LXXXIX: 7. sp. undt. d Walcott-..- Sp: Undt-eqWalcott—-o-s..s------0+secennme= Not figured. Eostrophomena elegantula (Walcott).......--..---- XCV: 6, 6a-b. erecta [Nisusia (Jamesella)], Walcott........-.....- CI: 5, 5a-b. eros [Lingulella (Lingulepis)], (Walcott).........-.. XUXOXEX: 9; 9a. eryx [Acrothele matthewi], Walcott.........-.-.-.- LXI: 2. escasoni [ Obolus (Westonia)], (Matthew) esthonia [Schizambon?], Walcott. etheridgei [Huenella], Walcott............---------- LXXXIX: 9, 9a. etheridgei [Micromitra (Paterina)], (Tate).......... III: 10, 10a-c. euglyphus [Obolus (Westonia)], (Walcott)......... XLVIII: 1, la-f. eurekensis [Orusia?], (Walcott).........----.------- CI: 7, 7a. excelsis [Trematobolus], Walcott. LXXXII: 8, 8a-b. exigua [Lingulella (Lingulepis)], (Matthew)......-- XXXII: 4, 4a; XLII: 1, 1a-z. eximia [Lingula?], Barrande...............-..--.---X XXII: 3. exporrecta [Billingsella], (Linnarsson).......-.----- LXXXVIII:1, la-l. exporrecta rugosicostata [Billingsella], Walcott. --.. LXXXVIII: 2,2a-c. favosa [Obolella (Glyptias)], (Linmarsson).........- LV: 2, 2a-d. feistmanteli [Obolus], (Barrande)..........-...----- XII: 1, 1a-f; 9, 9a. ferruginea [Lingulella], Salter................-.---- XXIX: 1, la-w; XXIX: 2, 2a-f; XXX: 1; XXXI: 3, 3a-c; XXXV: 4, 4a-b. ef. ferruginea [Lingulella], Walcott... festinata [Nisusia], (Billings)...........-.-..------- C: 1, 1a-j; 2, 2a-c; Text fig. 6, p. 299. festinata transversa [Nisusia], (Walcott).....-.----- C: 4, 4a-b. finkelnburgi [Finkelnburgia], (Walcott)...........-XCIII: 2, 2a-e. Finkelnburgia finkelnburgi (Walcott) ......-.-.---- XCIII: 2, 2a-e. ‘osceolal (Walcott) eccccc- cere <= eee CLlbe 1, dah. osceola corrugata (Walcott).......-...------- Not, figured. finlandensis [Obolus (Westonia)], Walcott........- XLVIII: 3, 3a-b. flumenis [Lingulella], (Matthew)...........-.------ XXXYV: 6, 6a-b. (Fordinia) bellulus [Obolus], (Walcott).....-....-- LI: 3, 3a-f. gilberti [Obolus], Walcott................-.-- LI: 5, 5a-d. perfectus [Obolus], Walcott... formosa [Mickwitzia], (Wiman).. fragilis [Obolus], (Walcott)..-........- Ssoacadasenes LXIIT: 10, 10a-d. SeGagoconsss6 VI: 3, 3a-c. XXII: 5, 5a-e. franklinensis [Lingulella], (Walcott)...........-.-.-X XVI: 3, 3a-b. fuchsi [Lingulella], Redlich................--.----- SOXXIX: 2, 20-c; 3. gamagei [Acrothele], (Hobbs) LX: 5, 5a-c. gemma [Acrotreta], Billings...........-.....------- LXVI: 1, la-b. gemma [Bicia], (Billings)..........-.--.----------- L: 1, la-n. gemmula [Acrotreta], Matthew................---- LXVI: 3, 3a-c; LXXVII: 5, 5a-f. gilberti [Obolus (Fordinia)], Walcott........-...--. LI: 5, 5a-d. girtyi [Linnarssonella], Walcott............--.----- LXXVIII: 5, 5a; LXXIX: 1, la-r. (Glyptias) favosa [Obolella], (Linnarsson)..-....-.-- LV: 2, 2a-d. gracia [Acrotreta], Walcott...............-..--....-XLVI: 5, 5a-d. grandis [Lingulella], (Matthew)...........---.-.--.X XXVIII: 2,2a-f. grandis [Lingulella ls-vis], Matthew mENSeXC TAC! granulata [Acrothele (Redlichella)], (Linnarsson) ..LVI: 2, 2a-n. granulata [Botsfordia], (Redlich) -LVII: 4, 4a-r. granulata [Discinolepis], Waagen........-..-..--.- LXXXI: 3, 2a-b. granulata [Kutorgina], Matthew..............---.- V: 5, 5a-c. granvillensis [Lingulella], Walcott....... ae XXII: 1, la-d. gregwa [Lingulella (Lingulepis)], (Matthew)... XLIV: 1, 1a-p. gregwa robusta [Lingulella (Lingulepis)],(Matthew). Not figured. groomi [Obolella]; Matley...........-.-......-.---- Text fig. 52, p. 596. gulielmi [Discinopsis] (Matthew)........-.--.------ LXXXII: 5, 5a-c. harlanensis [Wimanella], (Walcott). .-LXXXVII: 5, 5a-d. hastingsensis [Eoorthis], (Walcott) ................- XCIV: 3, 3a-c. haydeni [Micromiitra], Waleott..............-.--..- Text figs. 20A-D, p- 338. hayesi [Lingulella], (Walcott)..... --XXV: 1, la-j. heberti [Lingulella], Barrois..... --XXXIX: 11, lla-c. helena [Lingulella], (Walcott)...................-.- XXIV: 3, 3a-d. helena [Protorthis], Walcott...............-------- XCIX: 4, 4a-b. Helmersenia ladogensis (Jeremejew) ----L XIII: 7, 7a-f. hera [Acrothele subsidua], Walcott...........------ CAMBRIAN BRACHIOPODA. hicksi [Billingsella], (Salter MS.) (Davidson) - highlandensis [Billingsella], (Walcott)....... -XCVIE. 7, 7a-f. LXXXVII: 4, 4a-c, Huenella abnormis (Walcott)...........-.--------- CITI: 2, 2a-m; Text fig. 13, p. 299. billingsi (Walcott).........-..-..------------ CII: 5, 5a-c. etheridgei Walcott...........-....-.-.-.---.- LXXXIX: 9, 9a. lesleyitWialcott.-<<-- ccc cccecmen earn caesar Text figs. 75A-C, p. 807. orfentalis (Walcott) . CIV: 3 3a-b. texana (Walcott)..........---- .-CIIL: 1, la-i. texana lzviusculus (Walcott) = Not figured. vermontana Walcott...........-..----.----.- Text fig. 76, p. 809. humillima [Lingulella?], (Barrande) XXX: 12. hunnebergensis [Protorthis?], Walcott............- XCV;: 5, 5a-c. ida [Elkania], (Billings) .......-......----.---.----- XXX: 20, 20a; LI: 4, 4a-c. idahoensis [Acrotreta], Walcott........-.-.--------- LXV: 1, 1a-i; LXVIII: 2,.2a-g. ef. idahoensis [Acrotreta], Walcott. Not figured. idahoensis alta [Acrotreta], Walcott. . idahoensis sulcata[Acrotreta], Walcott............. LXV: 5. iddingsi[Eoorthis], (Walcott).......-.- -XCI: 3, 3a-b. inchoans [Acrotreta], (Barrande)... -XV: 7, 7a. indianola [Eoorthis], (Walcott)....- -XCIV: 1t, 2, 2a-h. inflata [Acrotreta], (Matthew).......-...--.-------- LXXVI: 1, la-k; 2, 2a. ? inflatus [Obolus], Westergard.......--...-.------ Not figured. ingricus[Obolus apollinis], (Eichwald).........-..-- Not figured. ino [Lingulella], (Walcott)....-..-...--.-----------X XVI: 4, 4a-b. insignis [Trematobolus], Matthew- . insons [Lingulella?], (Barrande) -...-- insulie [Lingulella atava], (Matthew) - -LXXXIV: 5, 5a-¢. _XXXII: 2, 2ae. _.XXXV: 8, 8a. intermedia [Acrothele], Linnarsson..........------- LVI: 3, 3a-d. inyoensis [Wimanella], Walcott..........---------- Text figs. 63A-B, p. 747. iole [Lingulella], (Billings)........-..-.--..-------- XXVII: 5, 5a. (Iphidella) louise [Micromitra], Walcott.........-.- Text figs. 31A-B, p. 359 nyssa [Micromitra], Walcott.........---.-.--- TIT: 9, 9a. ornatella [Micromitra], (Linnarsson).....-...- III: 6, 6a-d. pannula [Micromitra], (White).....-..---..-- IV: 1, 1a-t; 3, 3a; Text fig. 32, p. 362. pannula maladensis [Micromitra], (Walcott).-IV: 2, 2a-g. pannula ophirensis [Micromitra], (Walcott)...IV: 4, 4a-f. iphis [Obolus (Westonia)], Walcott. -.-X LIX: 4, 4a-d. irene [Lingulella], (Billings)........ XXVII: 6, 6a. iris [Lingulella], (Billings).....-.--.----.- PeE eee XeXoyil1 >) ismene [Obolus], Walcott.......----.-------------- XI: 3, 3a-b. isse [Lingulella], (Walcott)......-.-.-.-.------....- XX XIX: 4, 4a-b; Text figs. 43A-F, p. 510. (Jamesella) amii[Nisusia], Walcott.......--..--.-- CI: 6, 6a-b. argenta [Nisusia], Walcott...............----- CI: 9, 9a-b. erecta [Nisusia], Walcott....- ? kanabensis [Nisusia] Walcott ......-..----. Not figured. kuthani[Nisusia], (Pompeckj)....-...----.-- CI: 4, 4a-b. lowi[Nisusia], Walcott................-.-.-.- Text figs. 61A-D, p. 734. nautes [Nisusia], (Walcott)...........-....--- XCIII: 6, 6a-b. pellico [Nisusia], (de Verneuil and Barrande)..XCVII: 2, 2a-b. perpasta [Nisusia], (Pompeckj).......--..---- CI: 1, 1la-h. perpasta macra [Nisusia], (Pompeckj)......-- CI: 3, 3a. perpasta subquadrata[Nisusia], (Pompeckj)..CI: 2, 2a-b. spencei[Nisusia], (Walcott).........-....-..- XCIM: 7, 7a; Text fig. 62, p. 737. utahensis [Nisusia]. Walcott........----.----- CI: 10, 10a. jamesi[ Plectorthis], (Hall) XCVI: 5, 5a-c. johannensis [Eoorthis], (Matthew).....----.-------XCVII: 10, 10a. kanabensis [Nisusia? (Jamesella?)], Walcott.......- Not figured. kayseri[Eoorthis], (Walcott)..........-.-.-.-..---- XCVII: 6, 6a-b. kempanum [Trematobolus], (Matthew)....----.--- LXXXIII: 1, 1la-o. Keyserlingia buchi (de Verneuil)....-.....-.------- LXXXI: 4, 4a-e. kichouensis [Eoorthis], (Walcott) - - LXXXLX: 5. kiurensis [Lingulella], (Waagen).........-.-------- XXX: 5, 5a; 6, 6a. kuthani [Nisusia (Jamesella)], (Pompeckj) CI: 4, 4a-b. kutorgai [Acrotreta], Walcott...........-.--.------ LXY: 3,3a-e, g-k; Text fig. 58; p. 692. Kutorgina cingulata (Billings).......-......------- V: 1, 1a-s; Text figs. 3 and 8, p. 299, and 50A-C, p. 581. INDEX. Kutorgina granulata Matthew. . peculiaris (Tate)..... perugata Wialcott.-. 2-2 cee 2 oo cece neewnne sardiniaensis Walcott sp. undt. Walcott labradorica [Micromitra (Paterina)], ( Billings)-- labradorica orientalis [Micromitra (Paterina)], (Wal- .-Not figured. Il: 2, 2a-f. ((YYNCO) Reneicn-maccnscetnoscosossaone- II: 3, 3a-f. labradorica utahensis [Micromitra (Paterina)], (Wal- COLL) Bees a neneree eee rates a eee II: 8, 8a; . Text fig. 24, p. 350. labradorica var. [Micromitra (Paterina)] Walcott..-Not figured. ladogensis [Helmersenia], (Jeremejew) -LXIII: 7, 7a-f. levis [Acrothele subsidua], Walcott.........------- Not figured. levis [Lingulella], Matthew. ..........---------- _XIX: 4, 4a-b. leevis grandis [Lingulella}, Matthew. -.- ~ LX: 4c. levis [Protorthis], Walcott............-.---.---.--- XCIX: 6, 6a-b. leeviusculus [Boorthis wichitaensis], (Walcott) ...-.XCIV: 1p-s. leeviusculus [Huenella texana] (Walcott) Not figured. lamborni [Obolus], (Meek)........------- .-.X NII; 2;2a-n. lamborni minimus [Obolus], (Walcott). -- ..- XV: 4, 4a-b. lamellosus [Obolus (Westonia?)], (Barrande).......XII: 7, 7a-d. lata [Acrothele matthewi], Matthew. -...-...-.------ LXI: 3. lateralis [Syntrophia], (Whitfield)........-....----- CII: 6, 6a-g; Text fig. 11, p. 299. latourensis [Protorthis], (Matthew)..........---.---XCIX: 3, 3a-d. leda [Obolus tetonensis], Walcott............------- Not figured. lens [Lingulella], (Matthew).........---.-.---------XXXUI 1, la-d. lens [Obolus (Paleobolus) bretonensis], (Matthew). Not figured. lenticularis [Orusia], (Wahlenberg)........---------XCVIII: 1, la-p; 2, 2a-k; 3, 3a—b; 6, 6a-d. lenticularis atrypoides [Orusia], (Matthew).......-- XCVII: 5. lenticularis lyncioides [Orusia], (Matthew) --..----- XCVIII: 4. leos [Lingulella], (Walcott)............---.--------- XXIV: 2, 2a-c. lepis [Lingulella], (Salter)...............-.---.----- XXXI: 4, 4a-f. XIV: 5, 5a-b. Text figs. 75A-C, p. 807. levisensis [Acrothele], Walcott ....-.....----------- LXXXI: 12, 12a-b. limGensis [Acrotreta uplandica], (Wiman) ---L XX: 4, 4a-c. lindstrémi [Billingsella], (Linmarsson)...-........-- LXXXVII: 6, 6a-f. lindstr6mi [Obolella ?], Walcott ......-..----------- LV: 4, 4a. lineclata [Lingulella], (Walcott)..........------- -XLVIII: 2, 2a-l. Lingula anatina Bruguiére...........-..----------- Text figs. 34C-D, p. 374. Lingula? eximia Barrande...........----.---------X- XXII: 3. Lingulella acutangula (Roemer)......--------------X VII: 1, 1la-o. agnostorum (Wallerius)......--..------------ XK: 15. amplal (Owen) eaeee seas XXVIII: 1, 1a-j. arguta (Walcott). atava (Matthew).-.-.......----.-- XXIV: 5,5a-b. XXXY: 5,5a-h. atava insule (Matthew) XXXV: 8, 8a. augai QvWalCOth)ss---s-ss--serc+-->----== === XXIV: 6, 6a-g. bellaj@Wialcott)2=-eo-cs-- ee -=-- <9 == -----X1TX: 2, 2a-g5 XXXVI: 4. bellula (Walcott): <<< 22.2. -- 2 cree == XIX: 1, la-e. pillingsiana (Whiteaves) -..... --X XIX: 3, 3a. bornemanni (Walcott) --....-- .-X XX: 18, 18a-c. butts! Walcott. -.-.----.-.-- XXIX: 4, 4a-b. Ganial G@iiralcotb) een ate ses eee nae seen seems XXXYV: 3, 3a-d. edensi@Bacrande) seme sees aan ae eee XXX: 8. clarkei Walcott. --.....-.-..----.------------ Text figs. 42A—D, p. 436. collicia (Matthew). .......-...--.------------ XXXV: 1, 1a-f: 2, 2a-d. concinna Matthew........-..---------------- XXXII: 2, 2a-h; XXXIV: 1, la-r. cuneola (‘Whitfield)..--..---.....----.------- XXVII: 7, 7a-b. damesi (Walcott)... -- bee ne OOS EN:! 8; 8a=C: dayidsoni (Barrande)...........--.-.-------- XXXII: 1, la-e. davis (MCCOy)seceseece seme cee semen XOX: 2, 2a; XXAXI: 6, 6a-h. Bot Lingulella delgadoi Walcott............0-e-e--2---- XXIX: 6, 6a-c. desiderata (Walcott) XX: 4, 4a-c; 5, 5a-j. dubialG@walcott)s--aceenceeesesees XIV: 4, 4a. ellsi (Walcott).... XIX: 3, 3a-c. ferruginea Salter XIX: 1, la-w; XIX: 2, 2a-f; XXX: 1; XXXI: 3, 3a-c; XXXV: 4, 4a-b. cf. ferruginea Walcott.............----------- XXX: 4. flumenis (Matthew)......... XXXYV: 6, 6a-b. franklinensis (Walcott)...........-.--------- XXVI: 3, 3a-b. fuchsi Redlich eopece eo Ls 2, 28-C; 3. grandis (Matthew)........-- XXXVIII: 2, 2a-£ granvillensis Walcott...... veccecesdcs I, la-d! hayesi (Walcott)...... See eee RONG V cL LA] 5 hheberti Barrois. 2.2... .Cs levis Walcott. So ceieeeees ne eeeeok ClN7/16,;08-Ds latourensis (Matthew) ..-XCIX: 3, 3a-d. quacoensis (Matthew) XCIX: 2, 2a-e. wingi Walcott..-...-. XCIII: 5, 5a-c. sp. undt. Walcott Not figured. Protorthis (Loperia) dugaldensis Walcott......---- XCIX: 5, 5a-j. pulchra [Botsfordia], (Matthew)......----.-.------- LXII: 5, 5a-l. pumila [Lingulella (Lingulepis)], (Matthew) -....-- XLV: 3, 3a. pumpellyi [Billingsella], Walcott.........-------...-XCVII: 8, 8a-c. punctata [Lingulella], (Walcott)...........---------XX: 6, 6a. pusilla [Micromitra], (Linnarsson)...-...-..---.---- III: 2, 2a-c. puteis [Acrothele avia], Matthew ...-.-...---.----- Not figured. pygmiea [Lingulella (Lingulepis)], (Salter)..-......- XXX: 10. pyxidicula [Acrotreta], White..........-..--------- LXIX: 2, 2a-f; 3, 3a-f. quacoensis [Protorthis], (Matthew)......---- quadrilateralis [Lingulella], (Walcott) quadrilineata [Acrothele], Pompeckj....-..--.----- Quebecia circe (Billings) ..-.-.-.---------+---------- } quenstedti [Obolus apollinis], (Mickwitz) .........- Text figs. 34A-B, p- 374. radula [Lingulella], Matthew .........-.-.--------- XLV; 1, la-1. randomensis [Lingulella], (Walcott) -. rara | Acrothele], (Walcott) rara[Nisusia], Walcott......-.....-------- XEXT; 5, 5a: .-LXIIT: 4, 4a. .- Text fig. 60, p. 730. recurva[Volborthia], (Kutorga) ........------------ T: 6, 6a-e; Text figs. 33A-B, p. 366. (Redlichella) granulata [Acrothele], (Linnarsson)...L VI: 2, 2a—n. refulgens [Obolus], Matthew-..........--.----------- IX: 2, 2a-d.. remnicha [Eoorthis], (N. H. Winchell)............-XCI: 1, la-s; XCII: 2, 2a-d; 3, 3a-e; Text fig. 7, p. 299. remnicha suleata [Eoorthis], (Walcott) ....---.----- XCII: 1, 1a-c. remnicha texana [Eoorthis], (Walcott) ..-..- remnicha winfieldensis [Eoorthis], (Walcott) -- .-XCII: 4, 4a-g. XCI: 2,2a-e. retroflexa [ Billingsella], (Matthew) ..........--.---- XC: 1,la-h. rhea [|Obolus], Walcott...........-..--.---.-.----=- LX:) 1, 1a-c. tichthofeni [Billingsella], Walcott -- LUXXXIX: 1. roberti[Lingulella (Lingulepis)], (Matthew) .......X XX VII: 4, 4a-d. robusta[Lingulella (Lingulepis) gregwa], (Matthew). Not figured. rogersi[Obolus (Westonia)], (Walcott) ...-.-...----- XLII: 2, 2a-d. rokitzanensis[Obolus ?], Barrande........---------- XII: 6 romingeri[Billingsella], (Barrande).............-..- XC: 2,2a-n. Rustella edsoni Walcott............---.-.---------- I: 1, 1a-e. ? major (Matthew) . Text fig. 19, p. 328. sabrinse [Acrotreta], (Callaway) ....--.------------- LX XIII: 5, pa saffordi [Wimanella], (Walcott) .........----------- LXXXVII: 7 sagittalis [Acrotreta], (Salter)............----------- LXXI: 2, aes ‘3 3a-j. efssagittalis!pAcrotretal:-.----s--ss--erse= sine === = Not figured. sagittalis magna [Acrotreta], (Matthew) . sagittalis taconica [Acrotreta], (Walcott) sagittalis transversa [Acrotreta], (Hartt) --LXVI: 4, 4a-f. .-LXXI: 1, la-o. .-L XXII: 1, la-k. salemensis [ Billingsella], (Walcott) ..-...-..-------- LXXXVII:3, 3a. saltensis [Eoorthis], (Kayser).....-.--.------------- XCVII: 11. salteri [Obolus (Bréggeria)], (Holl).......---------- XIII: 1, la-n; XV: 4, 4a-d. sandbergi [Otusia], (N. HM. Winchell).......-.-...-- SCN 4, 4a-d. sardiniaensis [Kutorgina], Walcott. . : 4,4a-c. Schizambon? esthonia Walcott.........------------ LXXXIV: 4. manitouensis Walcott. .- LXXXIV: 3, 3a-e. priscus Matthew... .--- <2 2-22 ese. eee nn wine = LXXXIV: 2, 2a-e. typicalisaWialcott.-.seesseeetee sea saa LXXXIV: 1,1a-d. Schizopholis rugosa Waagen.....---.--------------- T: 4¢; LXXXI: 1, la-c. LXX: 1, 1a-s. ~- XM: 19, 19a-e. schmalenseei [Acrotreta], Walcott schmalenseei [Obolus], (Walcott)......--------- schmidti [Obolus], Mickwitz........--.-----.------ XV: lla-c. (Schmidtia) acuminatus [Obolus], Mickwitz ....--- XIV: 2,2a-c. celatus [Obolus], (Volborth) XIV: 1, la-c. crassus [Obolus], Mickwitz.....---.---------- XIV: 4, 4a-d. obtusus [Obolus], Mickwitz........-.--------XIV: 3,3a-c. schucherti [Lingulella], (Walcott) ....-- -X XI: 6. Schuchertina cambria Walcott. -....-- -LI: 6, 6a-m. scotica [Micromitra], Walcott..........--.---------- Text figs. 21A-C, p. 340. sculptilis [Micromitra], (Meek)...---...------------ III: 5, 5a-e sculptilis endlichi [Micromitra], Walcott. seebachi [Acrotreta], Walcott.--.--...--------- --- Text fig. 22, p. 342. --LXXVII: 3, 3a. selwyni [Obolus], (Matthew)........--.------------ XXXVI: 1, la-h; 2, 2a-b; XXXVII: 1, la-f. septalis [Obolus], (Walcott)....--.-..------------- XXXIV: 2, 2a; XNIII: 3d. sequens [Lingulella (Lingulepis) acuminata], Wal- (ilinesoascoc soteacobecdnSeneasoscegcads Text figs. 46A-B, p. dal. sera [Acrothyra], (Matthew)..-..----------+-------- LXXX: 4, 4a-c; 5, 5a-d; 6, 6a-i; 7, 7a-b; 8?. shansiensis [Obolus], Walcott -.-.....-------------- XI: 7, 7a-c. shantungensis [Acrotreta], Walcott......----------- LXIX: 5, 5a-e shelbyensis [Wimanella], Walcott. .-.-------------- II: 9, 9a. siemiradzkii [Lingulella], (Walcott) ..-...--------- EXSXEXGI 22a: signalis [Acrotreta], Walcott........-.-------------- LXIX: 4. signata [Acrothyra], Matthew’ ......--------------- LXXX: 1, la-d signata [Lingulella], (Barrande)......------------- e.0.0; Gauls signata orta [Acrothyra], Matthew-.......---------- LXXX: 3, 3a-b. signata prima [Acrothyra], Matthew-.--..-- -LXXX: 2, 2a-b. siluricus [Obolus (Mickwitzella)], (Eichw: =). XV: 1, la-c. similis [Lingulella], (Walcott)-.........-------------4 X XI: 2, 2a-j;3,3a-d. simplex [Lingulella ?], (Barrande).-....-------------X XXII: 4, 4a-b. simplex [Wimanella], Walcott.--....-.------------- LXXXIX: 2, 2a-e; Text fig. 64, p. 748 sinoe [Obolus], (Walcott) sseeeeee eee re eae NONI 2, 2a-h. Siphonotreta dubia Walcott-...--..---------- -LXXXI: 7, 7a-b. unguiculata (Eichwald) -LXXXI: 6, 6a-e. verrucosa (Bichwald).-..-------------- -LXXXI: 5, 5a-b. smithi [Obolus], Walcott. .--....---------------+--- Text figs. 38A-B, p. 416. socialis [Acrotreta], von Seebach......-.------------ LXXIII: 3, 3a-c; 4, 4a-e. 362 spatula [Lingulella (Lingulepis)], (Walcott)......-. XIX: 5, 5a-b. spencei [Nisusia (Jamesella)], (Walcott).........-.- XCIII: 7, 7a; Text fig. 62, p. 737 spinosa [Acrotreta], Walcott..........-.....-------- LXXIX: 4, 4a-g. spissus [Obolus (Lingulobolus)], (Billings) . XVI: 2, 2a-k; XLII: 3, 3a. spurri [Acrothele], Walcott.............---.-------- LX: 3, 3a-c. squamosa [Lingulella (Lingulepis ?)], (Hall)..-.--.- XXX: 9. starri [Lingulella (Lingulepis)], (Matthew)-........ XXXVII: 2, 2a-b. stoneanus [Obolus (Westonia)], (Whitfield)......-. XXVIII: 2, 2a-g; XLIX: 2, 2a. stissingensis [Micromitra (Paterina)], (Dwight).....III: 1, la-e. stissingensisiora;Walcott-2.----:-.-----2--2 ese see Not figured. striata [Billingsella], Walcott..............-....--.- LXXXVI: 4, 4a-c. stuarti [Micromitra (Paterina)], Walcott-.......-..- Text figs. 26A-B, p. 355. subconica [Acrotreta], Kutorga.........-.---------- LX XIII: 2, 2a-i. subequata [Dalmanella], (Conrad).........---.----- Text fig. 2, p. 299. subquadrata [Nisusia (Jamesella) perpasta], (Pom- 1d a) be soosascceonbeSoesassenccerongsed CI: 2, 2a-b. subsidua [Acrothele], (White) -........-- .-LX: 1, la-o; 8. subsidua hera [Acrothele], (Walcott)... - aes bp: Oh subsidua levis [Acrothele], Walcott............---- Not figured. suleata [Acrotreta idahoensis], Walcott........-..-- LXV: 5. suleata [Eoorthis remnicha], (Walcott).......- .--XCII: 1, la-c. sulcatus [Discinopsis?], Walcott..........-.-.-.---- LXXXII: 6. superba [Micromitra (Paterina)], (Walcott).........II: 7, 7a-f; Text figs. 27A-B, p. 355. swantonensis [Micromitra (Paterina) labradorica], OWralcott) neice aes 5 Sus S35 eee Il: 3, 3a-f. Swantonia antiquata (Billings)..............-.-.-.. CIV: 5, 5a-b. weeksi Walcott Syntrophia alata Walcott......-/..--...----------: CIIT: 3, 3a-d. barabuensis (A. Winchell). -............-...- CII: 1, la-g. calcifera (Billings) ---CIV: 1, 1a-i. cambria Walcottecesepe caters eee eee Text figs. 72A-D, p.- 800. Campbelliiwalcottsarscas sec ane Text figs. 73A-F, p. 801. lateralis! @Wibitheld) \scmseciotactcecl eee CII: 6,6a-g; Text fig. 11, p. 299. MundinaiWalcottess.- see ene e ee eee CI: 4, 4a-d. onbhiaaWialcottos-s-2-—- eases ee CIV: 4, 4a-b. primordialis (Whitfield)...................-.. CIT: 2, 2a-e. primordialis argia Walcott eeCHci3: TOtUNdatayWalcotlssoc eee eae een eee CIII: 4, 4a-e. PAUTERIAAVY COU arsesetsiectee ett incie ine oe ees Text fig. 74, p. 805. taconica [ Acrotreta sagittalis], (Walcott). .......... LXXI: 1, 1la-o. tarpa [Lingulella], (Walcott)..........-..-.....---.X XIII: 2, 2a-c. tatei[ Eoorthis], (Etheridge)............. -XCVII: 15, 15a. tennesseensis[ Linnarssonella], Walcott LXXIX: 3, 3a-k. tetonensis [ Acrotreta microscopica], Walcott. ......L XVII: 3, 3a-d. tetonensis[Obolus], Walcott..........-...-. --IX: 5, 5a-d. tetonensis leda[Obolus], Walcott .......-- -Not figured. tetonensis ninus[Obolus], Walcott................- VIII: 11-10; XI: 1, la-g. texana[Eoorthis remnicha], (Walcott)........-...- XCII: 4, 4a-g. texana [Huenella], (Walcott).............. --CIII: 1, 1a-i. texana leviusculus [Huenella], (Walcott).........- Not figured. texana[Lingulella], Walcott.........-.....-........ XLIX: 3, 3a. themis [Obolus (Westonia)], Walcott... ... XI: 2, 2a-c. thyone[Eoorthis], Walcott... ..................-.-- Text figs. 70A-C, : p- 789. torrentis[ Lingulella], (Matthew) ...................XX XV: 7. torrentis[Obolus?], Matthew...........--...--..--. Not figured. transversa[ Acrotreta sagittalis], (Hartt). -LXXII: 1, la-k. transversa[ Linnarssonella], Walcott..............-- LXXVIII: 6, 6a-c. transversa[ Nisusia festinata], (Walcott)............ C: 4, da-b. ..LX XXII: 8, 8a-b. -LXXXIV: 5, 5a-c. ..LXXXIII: 1, 1a-o. Trematobolus excelsis Walcott.........- insignis Matthew..:--......-....-... kempanum (Matthew).............- Dpristinus|(Matthew) ees-2- ees see eee eee LXXXIII: 2, 2a-h; LXXXIV: 6. triangularis [Obolus], Mickwitz, .................... Not figured. triparilis [LinguleNa], (Matthew)-........... Vo setsc ii XLV: 2, 2a-f; Text figs. 44a-I, p. 537. ---XOV: 3. tullbergi[ Eoorthis], (Walcott) CAMBRIAN BRACHIOPODA. tumida [Lingulella], Matthew............-......-.- XXIV: 7, 7a-d. turneri [Acrothele], Walcott...........--.-.----...- LX: 7, 7a. typicalis [Schizambon], Walcott............----..-- LXXXIV: 1, la-d. ulrichi [Acrotreta], Walcott....-.......-.-- --LUXXVII: 3. undosa [Micromitra (Paterina)], (Moberg).-...--... Text figs. 28A-C, p. 356. unguiculata [Siphonotreta], (Eichwald)-.-........... LXXXI: 6, 6a-e. unxia [Syntrophia], Walcott..........-..-.-- upis [ Lingulella], (Walcott) uplandica[Acrotreta], Wiman...........--- uplandica liméensis [ Acrotreta], (Wiman).- urania [Linnarssonellal, Walcott utahensis [Micromitra (Paterina) labradorica], - Text fig. 74, p. 805. -XXXVI: 3, 3a. -LXX: 3, 3a-c. -LXX: 4, 4a-c. --L XXVIII: 9, 9a-c. Wralcoptss2 25 5)isccee soe one era II: 8, 8a; Text fig. 24, p. 350. utahensis [Nisusia (Jamesella)], Walcott...........- CI: 10, 10a. utahensis [Otusia], (Walcott).........- --LXXXIX: 3, 3a-c. varians [Orbiculoidea], (Barrande)...-......-...-.- LXXXI: 8. vaticina |Nisusia ?], (de Verneuil and Barrande)...XCVII: 3, 3a-b. vermilionensis [Obolella], Walcott.........-.-.-.-.- Text figs. 53A-E, p.- 598, vermontana [Huenella], Walcott ..........-.-..-..- Text fig. 76, p. 809, verrucosa [Siphonotreta], (Eichwald) .--UXXXI: 5, 5a-b. villaboimensis [Acrothele], Delgado ....-...-.-.--.- Not figured. volborthi [Obolus], Mickwitz........---.---..---.-- Not figured. Volborthia recurva (Kutorga).......-. Be AAs memese I: 6, 6a-e; Text figs. 33A-B, p. 366. wanneri [Yorkia], Walcott...............------+--- LXXXII: 1, la-i. wanniecki [Lingulella], Redlich.....-.--...-.-..--- XXXIX: 1, la-n. wapta [Micromitra (Paterina)], Walcott...........- Text figs. 29A-B, p. 357. warthi [Neobolus], Waagen......-....---..--.-.--- T: 3; 4, 4a-b; 5, 5a; LXXXI: 2, 2a-h. Text figs. 47A-B, p- 567. warthi [Wynnia], (Waagen).....--.------.-----0+-- LXXXIX: 4, 4a-t; Text fig. 68, p. 771. wasatchensis [Obolus (Westonia)}, Walcott.....-.-- XLIX: 5, 5a; Text figs. 41A-F, p. 467. washingtonensis [Yorkia?], Walcott...........-...- LXXXIIX 2, 2a. weeksi [Swantonia], Walcott. ... welleri [Lingulella], (Walcott). - XXXVIII: 4, 4a-b. (Westonia) Alandensis [Obolus], Walcott..........- XLVIII: 6, Ga. faviroray[Obolus] (Cel all) 2 eee ase eee XLVI: 1, la-h. balticus [Obolus], Walcott............-......XLVII: 7, 7a-b. blackwelderi [Obolus], Walcott XX XIX: 10, 10a-c. bottnicus [Obolus], (Wiman).............-...- XLVIII: 4, 4a-e. chuarensis [Obolus], (Walcott)......-..-..-.- XXYV: 2, 2a-e. dartoni [Obolus], Walcott..............-.---- Text figs. 40A-C, p. 455. ella [Obolus], (Hall and Whitfield) ...........X XXIII: 3, 3a-c; > XLVII: 1, 1a-p. ella onaquiensis [Obolus], Walcott............XLIX: 6, 6a. elongatus [Obolus], Walcott...............-.- LXIIT: 8, 8a-d. escasoni [Obolus], (Matthew).........-.--.--. XLIX: 1, 1a-f. euglyphus [Obolus], (Walcott) .............-- XLVI: 1, 1a-f. finlandensis [Obolus], Walcott . XLVIII: 3, 3a-b. iphis [Obolus], Walcott...................-.- XLIX: 4, 4a-d. ? lamellosus [Obolus ?], (Barrande)...-....--- XII: 7, 7a-d. notchensis [Obolus], Walcott.............-..- LXIII: 9. rogersi [Obolus], (Walcott)...................X LIT: 2, 2a-d. stoneanus [Obolus], (Whitfield) .............. XXVIII: 2, 2a-g; XLIX: 2, 2a. themis [Obolus], Walcott............-------- XI: 2; 2a-c. wasatchensis [Obolus], Walcott......-...---- XLIX: 5, 5a; Text figs. 41A-F, p. 467. wimani [Obolus], Walcott...........-....--.-XLVIII: 5, 5a-b. whiteavesi [Bicia], Walcott. ............-..-.---..-- L: 2, 2a-e. whitfieldi [Billingsella], (Walcott)............-.2..- LXXXVI: 5, 5a. whitfieldi [Plectorthis], (N. H. Winchell) -...--...- XCVI: 3. wichitaensis [Eoorthis], (Walcott)-.-...-...-.---.--- XCIV: 1, 1a-0, lu. wichitaensis lzeviusculus [Eoorthis], (Walcott)......XCIV: 1p-s. williardi [Micromitra (Paterina)], Walcott.......-.- II: 9b-e; Text figs. 30A-E, p. 358. willisi [Obolus], (Walcott).......-...----.-..--+---- XXIII: 1, la-j. Wimanella ? anomala (Walcott).........--.-------- LXXXVII: 1, la-e. INDEX. Wimanella harlanensis (Walcott) LXXXVII: 5, 5a-d. inyoensishwialcotts.. --csecse nace oe eee eee Text figs. 63A-B, p. 747. Saftordil((Walcott):: 5-2. -sss6-----ceeee -LXXXVII: 7,7a. shelbyensis Walcott. II: 9,9a. SUMPIOXAW alCOLL ten sneeasena nae come eee LXXXIX: 2, 2a-e; Text fig. 64, p. 748. » wimani [Obolus (Westonia)], Walcott..............XLVIII: 5, 5a-b. wimani [Eoorthis], (Walcott).......... ----XCV: 4, 4a-d. winfieldensis [Eoorthis remnicha], (Walcott) ....... XCI: 2, 2a-e. wingi [Protorthis], Walcott..............-- XCIII: 5, 5a-c. winona [Lingulella], (Hall)...........- XVIII: 3,3a-b. winona convexa [Lingulella], (Walcott) . .. XVIII: 4, 4a-d. wirrialpensis [Obolella], Etheridge...............--- LV: 7,7a-b. wirthi [Lingulella], (Barrande)................-..-.X XX: 7. woodworthi [Acrothele], Walcott...............---- LX: 6. 363 worthenil [Obolus]iWaleottss eoee ec ssececcce cence IX: 5e; Text figs. 39A-D, p. 421. Wiynniatwarthi((Wadgen)-. c.oo csc cc cece clocekn = LXXXIX: 4, 4a-f; Text fig. 68, p. 771. yorkensis [Acrothele], Walcott.............-...--.-- LIX: 4, 4a-b. porkiamemi quell W alcottsscesss cn ss. sees seem asi LXXNXII: 4. ? orientalis Walcott -. ..-LUXXXII: 3, 3a. WAT eriNValCObtseowicemeeccetinicn nitric sis LXXNII: 1, la-i. ? washingtonensis Walcott.............-.---- LXXXII: 2,2a. ZeNO | [Hoorthis]wialcott-sscancwes scenes cece siete cle Text figs. 71A-B, p. 792. zenobia [Micromitra], Walcott.....--....------.--- Text fig. 23, p. 342. zetus [Obolus], (Walcott)....... == OVS) 8) 8a-C. zeus [Lingulella], Walcott... .. ..- Text fig. 45, p. 541. zoppi [Obolus?], Walcott...............------------ XXX: 16, 16a-b. Free egre |) Uyael rors bey AK jee ll Il | | | | | Te) N o N or Of —a) ei ° re) ro) So Ds o