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184 MOLLUSCA FROM MIOCENE AND LOWER PLIOCENE OF VIRGINIA AND NORTH CAROLINA but inconspicuous sutures. Nuclear whorls wanting. Each of remaining turns sculptured with 4 approximately equisized and equispaced spirals, very low, broad, and straplike, mounted with close-set, squarish tubercles, about 2 to each linear millimeter on the body whorl; the foundation bands on the earlier whorls almost or altogether obsolete, the tubercles sharper and more rounded, thus lending a beaded aspect to the sculpture of the posterior portion of the shell; a simple secondary introduced on the penultima at the medial line of the whorl, midway between the second and third primaries, later becoming wavy and inconspicuously beaded. Peripheral keel angular but not sharp, outlined by a broad, simple, spiral band. Base flattened, sculptured by strong, slightly rounded spirals varying somewhat in width and spacing, tending to become stronger and more distant in the umbilical region; interspaces sculptured with radiating incrementals. Aperture badly broken, probably angular, broader than it is high. Pillar smooth, concave, strengthened by the reflected callus. Umbilicus imperforate. The species, though described from a unique type, is sharply separated from all other forms of this area by the monotonous pyramidal outline, unbroken by any angula-rities or convexities of the whorls and by the 4 rather than 3 primary spirals upon the adolescents and the squarish tubercles which adorn the adult spirals. Among the Recent species, its nearest kin is perhaps Oalliostoma apicinwm Dall of the West Indian fauna, a slightly smaller, more elevated conch with a much finer, sharper sculpturing. Dimensions of holotype: Height 11.1 mm., maximum diameter 10.0 mm. Holotype: U.S.N.M. 325470. Type locality: Eight to 9 miles southeast of Greenville, Pitt County, N. C. Yorktown formation, zone 2. In the Oalliostoma philanthropum group, including the subspecies pontoni Mansfield (pl. 26, fig. 15) and 0. basicwm Dall (pl. 26, fig. 11), a guide fossil of zone 2 of the Yorktown formation in Virginia and North Carolina, 0. mitchelli (Conrad) (pl. 26, figs. 19, 23), and 0. ruffinii (H. C. Lea) (pl. 26, fig. 18), the posterior suture is overhung by the beaded peripheral keel of the preceding whorl. The group is further removed from 0. cheopsi by the 3 primary spirals on the early whorls and by the sharp well-rounded beads of the adult ornamentation. Distribution: Yorktown formation, 8 to 9 miles southeast of Greenville, Pitt County, N. C. Calliostoma carolinense Gardner, n. sp. Plate 26, figures 3, 4 Shell heavy, moderately low; the regularity of the pyramidal outline broken by the strong spiral cording. Whorls narrowly tabulated, 6 in number, including the protoconch, which is very small, probably of not more than one turn, and, in its decorticated condition, not readily differentiated from the conch. Initial sculpture on the conch of 3 spiral lirae, equal in size and spacing; a fourth spiral introduced on the next to the last whorl of the spire between the posterior and medial lirae, increasing somewhat in strength and persistent but not attaining the prominence of the original primaries; no other lirae intercalated: on adult whorls original posterior primary outlining the shoulder; the anterior, together with the stronger .outer basal spiral, forming the double peripheral keel; and the medial of the 3 original spirals, together with a fourth, symmetrically disposed between the peripheral and shoulder spirals. Base flattened, heavily sculptured with 4 additional broad straplike cords extending far within the aperture, separated by interspaces of approximately their own width; umbilical keel outlined by a similar spiral. Incremental sculpture microscopically fine. Suture distinct but not conspicuous, following the anterior of the peripheral cords, which is commonly partially visible as a thin, sharp thread directly behind the suture. Aperture transversely ovate. ·Outer margin imperfect, crenulated by the strong spirals. Parietal wall thinly glazed. Columellar margin concave, simple, reflected. Umbilical region excavated but not perforate. Dimensions of holotype: Height 9.8 mm., maximum diameter 11.2 mm. Holotype: U.S.N.M. 325472. Type locality: Hamilton Bluff on the Roanoke River, Martin County, N.C. Yorktown formation, zone 2. 0 alliostoma carolinense is characterized by the prominence of the primaries and the reduced number ·of the secondaries. It is, apparently, an end member of the 0. virginicwm group. Oalliostoma harrisianrum Olsson, 1916, seems from the description and the rather poor illustration to be intermediate between 0. carolinense and 0. virginicum s. s. In 0. carolinense the regularity of the profile is broken by the heavy spirals, but the profile of 0. harrisianum more closely resembles that of 0. virginicum. The number of spirals is more reduced in 0. carolinense than it is in either of the two species from Virginia and, with the possible exception of the peripheral spirals, they seem to be stronger than those of 0. harrisia1'1ffJJm. The North Atlantic species Oalliostoma occidentale Mighels and Adams, 1842, is similar in general aspect, but the 3 primary spirals are beaded on the juvenile shells, and the sculpture on the base of the adult is irregular and tends to become obsolete except toward the periphery and the umbilical area. Distribution: Yorktown formation, Hamilton Bluff on the Roanoke River, Martin County, N. C.
Calliostoma virginicum (Conrad) Plate 26, figure 12 1875. Zizyphinus virfJ.inicus Conrad, North Carolina Geol. Survey Rept., vol. 1, app. A, p. 22, pl. 4, .fig. 4. Type locality : Suffolk, V a. 'calliostoma virginicum gizehi Gardner, n. subsp. Plate 26, figures 16, 17 Shell moderately low, pyramidal. Whorls trapezoidal, regularly increasing in size, 5 to 6 in number. Protoconch decorticated, minute, probably of not much more than 1 volution. Initial sculpture of 3 equal and equidistant spirals, the anterior and posterior of which gradually become more prominent relatively and absolutely; intercalaries introduced on early whorls. Sculpture when fully developed, consisting of a single broad, simple, moderately elevated cord in front of the posterior suture, a similarly broad and elevated cord directly behind the anterior suture and, on the intermediate area, 4 to 8 fine, sharp lirae tending to alternate in size when numerous; 2 simple and moderately strong cords girdling the periphery and a fine, sharp threadlet intercalated between them. Suture line distinct but inconspicuous, following the anterior spiral of the double keel but rarely completely covering it, so that the carina is partially visible as a fine, sharp thread directly behind the suture. Base flattened, sculptured with 9 to 11 simple lirae, those nearer the axis the broader and the more irregular in size and spacing. Aperture somewhat broken, rudely rhomboidal; outer margin imperfect but obviously angulated at the periphery. Inner margili concave, reflected. Umbilical region slightly excavated but imperforate. Dimensions of holotype: Height, 9.2 mm. ; maximum diameter, 10.5 mm. Holotype: U.S.N.M. 325467. Type locality : Yorktown, V a. Yorktown formation, zone 2. 0 alliostoma virginicum gizehi exhibits a tendency toward an increase in the number of lirations accompanied by a corresponding decrease in their prominence. The subspecies, though distinct from 0. virginicum in general aspect, is merely the result of a relative and an absolute increase in the strength of the sculpture between the anterior and posterior carinae and a relative and absolute decrease in the strength of. the spirals delimiting the carinae. In some individuals, indeed, the spiral outlining the posterior keel is reduced until it is scarcely more prominent than the lira in front of it. In 0. labrosum (Conrad) (pl. 26, fig. 10) , a low and broadly biconic member of the same group, the general sculpture plan is constant, but the sculpture is greatly subdued. Distribution: Yorktown formation, Yorktown, York County, Va. PART 2. SCAPHOPOI>A AND GASTROPODA 185 Calliostoma hertfordense Gardner, n. sp. Plate 26, figures 13, 14 Shell depressed, pyramidal, terminating obtusely. Volutions 5. Protoconch not well differentiated, very small, of probably not more than 1 coil, smooth, immersed in the succeeding turn. Earliest whorls of conch ornamented with 3 strong spirals. Posterior spiral increasing in prominence with the establishment of the later sculpture, becoming wavy and finally beaded, and outlining the narrow shoulder. Anterior of the 3 spirals increasing similarly in strength, gradually assuming a beaded character, and delimiting the . anterior peripheral keel. Median spiral flattening; 2 low intercalaries introduced on the spire, 3 on the body whorl. A single, rather prominent, rounded thread revolving midway between the anterior keel and the anterior suture line on all but the earliest whorls. Suture not very distinct, separated from the posterior carina of the succeeding whorl by a shallow but welldefined channel. Peripheral keel obtuse, outlined by a rather strong, simple spiral; a second spiral, similar in strength and character, placed midway between it and the anterior beaded spiral. Base flattened, sculp· tured with about 9 rather feeble and irregular spirals; the 2 or 3 spirals in the umbilical region the strongest and separated by the widest interspaces; remaining lirae tending to fuse near the inner lip but becoming more distinct toward the labrum. Incrementals well developed on the body whorl both behind the periphery and on the base. Aperture subquadrate. Pillar slightly excavated, heavily calloused. Umbilical pit small, possibly pathologic. Dimensions of holotype: Height 7.3 mm., maximum diameter 8.8 mm. Holotype: U.S.N.M. 325469. . · Type locality: One and one-half miles above Murfreesboro, Hertford County, N. C. Yorktown formation. The diagnostic features of the species are the low, turbinate outline, the sutural channel separating the whorls, and the characteristic sculpture of 2 not very prominent, beaded spirals-the one posterior, the other anterior-and 3 or 4 low, subequal intermediate"lirae. The early whorls and the general sculpture plan of the adult are similar in 0. hertfordense and in 0. virginicum (Conrad). 0 alliostoma virginicwm is the larger shell and, relatively as well as absolutely, higher; the channelling between the sutures is deeper than in 0. hertfordense, and all the spirals are simple. The small umbilical perforation in the North Carolina species may be the result of the injury recorded by the scar. 0. virginicum is imperforate. 0. virginicurm gizehi is more closely comparable, but in the subspecies, also, the spirals are simple and the apical angle smaller. The type is unique.
Page 3: UNITED STATES DEPARTMENT OF THE INT
Page 21: Family RISSOINIDAE Genus RISSOINA D
Page 31: formations, Dominican Republic. Pli
Page 34: 206 MOLLUSCA FROM MIOCENE AND LOWER
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Page 51 and 52: Genus UROSALPINX Stimpson 1865. Uro
Page 53: Proportionally wider than F. cinere
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cose and the posterior siphonal .no
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Aesopus stearnsii (Tryon) is one of
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PLATES 24-38 281
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GEOLOGICAL SURVEY 12 18 25 32 7 2 2
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PLATE 26 FIGURES 1-2. Calliostoma n
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GEOLOGICAL SURVEY PROFESSIONAL PAPE
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GEOLOGICAL SURVF.Y PROFESSIONAL PAP
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7 GEOLOGICAL Sl"RVEy 8 9 3 GASTROPO
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PLATE 32 FIGURE 1. Ptychosalpinx fo
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GEOLOGICAL SURVEY PROFESSIONAL PAPE
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GEOLOGICAL SURVEY 7 GASTROPODS PROF
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