GASTROPODS: TROCHIDAE TO TURRITELLIDAE


i part, localities 138, 138a. Middle part, eastern area, localities 146, 147b, 147f, 147g, 147h, 153a, 155c; ovestern area, locality 161. Upper part, eastern area, locality 173; western area, locality 185. Cercado and nGurabo formations (middle Miocene), Dominican ]Republic. Bowden formation (middle Miocene), Jamaica.
 Genus Solariorbis Conrad
 Conrad, American Jour. Conch., v. 1, p. 30, 1865. [Type (logotype, Dall, Wagner Free Inst. Sci. Trans., v. 3, pt. 2,
 p. 414, 1892): Delptinsla depressa Lea, Eocene, Alabama.
 Subgenus Solariorbis s.s.
 The subgenus Soliariorbis s. s. is characterized by relatively large size, faint spiral sculpture (microscopically punctate in the type species), and a wide umbilical wall on the body whorl adjoining the aperture.
 Solariorbis (Solariorbis) strongylus Woodring, n. sp.
 Plate 17, figures 43-45
 Of medium size, thick-shelled, moderately depressed. Periphery faintly and bluntly angulated, except at and near peristome where it is rounded. Penult and part of preceding whorl sculptured with closely spaced spiral threads. Spirals become faint and even disappear on body whorl, but most persistent near suture and just above periphery. Under strong light base shows barely discernible microscopic spiral striation. Umbilicus moderately narrow, asymmetrical, bounded by a crude spiral ridge, which is slightly roughened by growth wrinkles. Parietal callus thin.
 Height 1.3 mm, diameter 2.4 mm (type). Height
 1.5 mm, diameter 3 mm (largest specimen).
 Type: USNM 561322; paratypes, Stanford Univ.
 Type locality: 138 (USGS 16909, Transisthmian Highway, 1.6 kilometers northeast of Canal Zone boundary, Panam ), lower part of Gatun formation.
 The weak sculpture and moderately narrow asymmetrical umbilicus are characteristic features of this species. It is represented by 13 specimens, all from the type locality.
 Occurrence: Lower part of Gatun formation (middle Miocene), localities 138, 138a.

 Subgenus Hapalorbis Woodring, n. subgen.
Type: Circulus liriope Bartsch, Recent, Gulf of California.
 The name Hapalorbis is proposed for a minor group of Solariorbis consisting of small carinate species that have a narrow umbilical wall on the body whorl adjoining the aperture. The type species has a spiral thread above and below the peripheral carina-formmg thread. Others have one to three threads below the periphery and one or two above. Still others have none below or above the periphery.


 The subgenus Systellomphalus (Pilsbry and Olsson, 1941, p. 48; type (orthotype): Systellomphalus perornatus Pilsbry and Olsson, Pliocene, Ecuador), with which Pilsbry and Olsson associated species closely allied to "Circulus" liriope, may be defined as embracing species that have axial riblets on spire whorls and axial wrinkles on the base of the body whorl adjoining the umbilicus.
 Hapalorbis is not known to have survived the Miocene in Caribbean waters.
 Solariorbis (Hapalorbis) hyptius hyptius Woodring, n. sp. and n.
 subsp.
 Plate 17, figures 16-18
 Small, thick-shelled, depressed, body whorl increasing rapidly in diameter. Periphery sharply or moderately carinate, except at and near peristome. Umbilicus very narrow, asymmetrical. Umbilical wall very narrow, the angulated umbilical border being inserted almost flush with base of body whorl where it emerges from umbilicns. Parietal callus moderately thick.
 Height 0.7 mm, diameter 1.4 mm (type).
 Type: USNM 561323; paratypes Stanford Univ.
 Type locality: 147b (USGS 6033c, Panama Railroad, about 3,500 feet (1,065 meters) southeast of Gatun railroad station, Canal Zone), middle part of Gatun formation.
 The very narrow and asymmetrical umbilicus, and very narrow umbilical wall are conspicuous and characteristic features of this species. It is closely related to the type of Hapalorbis: "Circulus'' liriope Bartsch (1911, p. 231, pl. 40, figs. 7-9), which is represented by the type and an imperfect specimen, both dredged at a depth of 21 fathoms off La Paz, Lower California. The fossils are smaller, more depressed, have a smaller more asymmetrical umbilicus and narrower umbilical wall, and lack a spiral thread above and below the peripheral carina.
 Solariorbis hyptius proper was found in the lower and middle parts of the Gatun formation, but is rare except at the type locality. The 68 specimens collected at the type locality and the 2 additional specimens from the middle part of the Gatun have remarkably uniform characters. The five specimens from the lower part, however, are not so sharply carinate and reach a slightly larger size.
 Occurrence: Lower and middle parts of Gatun formation (middle Miocene). Lower part, locality 138a. Middle part, localities 146, 147b, 147f.
 Solariorbis (Hapalorbis) hyptius anebus Woodring, n. subsp.
 Plate 17, figures 34-36
 Resembling S. hyptius proper, but larger and umbilicus correspondingly larger. Peripheral carina flanked above and below by a narrow low spiral thread.


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