GEOLOGY AND PALEONTOLOGY OF CANAL ZONE


 1947). Though the early whorls and growth line of the species from Panama are not known, it is without much doubt a close ally of T. subgrundifera, if not that species. The protoconch of T. subgrundifera is cylindrical, consisting of 1% strongly inflated whorls. Three spirals appear gradually and practically simultaneously on the first sculptured whorl: a strong middle spiral, a moderately strong anterior spiral (the carina-forming spiral of later whorls), and a weak posterior spiral. The growth-line sinus is very shallow and wide, and the growth-line angle very wide.
 T. subgrundifera is recorded from the Miocene of Colombia (Pilsbry and Brown, 1917, p. 35).
 Occurrence: Culebra formation (early Miocene),Gaillard Cut, locality 99d.
 Turritella venezuelana Hodson
 Plate 16, figures 8, 9
 Turritella venezuelana Hodson, Bull. Am. Paleontology, v. 11, no. 45, p. 32, pl. 21, figs. 4, 8, pl. 22, figs. 1, 6, 1926 [Itiocene
 (Oligocene-Miocene of Hodson), Venezuela].
 Turritella venezuelana quirosana Hodson, idem, p. 34, pl. 22, figs. 9, 10, pl. 24, fig. 1, 1926 [Miocene (Oligocene-Miocene of
 Hodson), Venezuela].
 Turrilella venezuetana watkinsi Hodson, idem, p. 34, pl. 22, fig. 8, 1926. [Miocene (Oligocene-Miocene of Hodson), Venezuela].
 Small, early whorls rapidly enlarging. Whorls moderately carinate at about anterior fourth or rounded. Sculpture consisting of 6 or 7 primary spirals. On some specimens a minor spiral is present in some interspaces. Earliest preserved whorls sculptured with three spirals, the posteriormost weak and the anteriormost forming the carina on later carinate whorls. Base sculptured with weak closely spaced minor spirals. Growth-line sinus very shallow and wide; growth-line angle very wide.
 Height (incomplete, 6 whorls) 15.3 mm, diameter 5.4 mm (larger figured specimen). Height (incomplete,
4 whorls) 23.5 mm, diameter 9.5 mm.
 Type: Paleontological Research Institution, Ithaca, N. Y.
 Type locality: Locality 6, Oil seep at Mene de Saladillo, 1Y kilometers southwest of Quir6s, District of Miranda, Zulia, Venezuela (Hodson and Hodson, 1931, p. 5), La Rosa formation (Sutton, 1946, p. 1694), early Miocene.
 This small species occurs in the Culebra formation. It shows considerable variation in whorl profile, in width of primary spirals, and in presence or absence of minor spirals. According to Hodson, it is variable in Venezuela also. The types of the three forms named by him were found at the same locality.
 Turritella venezuelana is closely related to T. subgrundifera, but evidently is not a small form of that species. T. subgrundifera is carinate (except the late


whorls of a few specimens), its early whorls enlarge less rapidly, and the posteriormost of the three spirals of early whorls appear at an earlier stage. Both species are representatives of Merriam's T. ocoyana stock (Merriam, 1941, p. 47).
 Occurrence: Culebra formation (early Miocene), Gaillard Cut, localities 99b, 107, 110, 111a, 112, 112a, 114. La Rosa formation (early Miocene), Zulia, Venezuela.
 Turritella abrupta Spieker Plate 23, figures 6, 15, 16
Turritella (Haustator) robusta Grzybowski, Neues Jahrb.,
 Beilage-Band 12, p. 646, pl. 20, fig. 3, 1899 (Miocene, Perd).
 Not T. robusta Gabb, 1864.
Turritella robusta Grzybowski, Woods, in Bosworth, Geology of
 the Tertiary and Quaternary periods in the north-west part of Peru, p. 110, pl. 18, fig. 4, pl. 19, fig. 1, 1922 (Miocene, Perd).
 Spieker, Johns Hopkins Univ. Studies in Geology, no. 3, p.
 84, pl. 4, fig. 5, 1922 (Miocene, Perd).
Turritella robusta var. abrupta Spieker, idem, p. 85, pl. 4, fig. 6,
 1922 (Miocene, Perd).
Turritella charana Spieker, idem, p. 86, pl. 4, fig. 7, 1922 (Miocene, Perd).
Turritella supraconcava Hanna and Israelsky, Calif. Acad. Sci.
 Proc., 4th ser., v. 14, no. 2, p. 59, 1925 (new name for T.
 robusta Grzybowski).
Turritella robusta fredeasi Hodson, Bull. Am. Paleontology,
 v. 11, no. 45, p. 13, pl. 5, figs. 1, 3, pl. 6, figs. 2, 5,pl. 7, figs.
 1, 6, 7, pl. 9, fig. 7, pl. 29, fig. 6, 1926 (Miocene, Venezuela). Turritella supraconcava var. fredeai Hodson, Weisbord, idem, v. 14, no. 54,p. 30, pl. 9, figs. 3, 4, 1929 (Miocene, Colombia). Turritella fredeai Hodson, Anderson, Calif. Acad. Sci. Proc., 4Cth ser., v. 18, no. 4, p. 119, pl. 17, fig. 1, 1929 (Miocene, Colomhia).
Turritella abrupta Spieker, Olsson, Bull. Am. Paleontology, v. 19,
 no. 68, p. 200, 1932 (Miocene, Perd). Merriam, Calif. Univ.
 Dept. Geol. Sci. Bull., v. 26, p. 48, pl. 29, fig. 4 ("cf."), pl. 30, fig. 6, pl. 31, figs. 2-4, 1941 (Miocene, Colombia, Venezuela). Marks, Bull. Am. Paleontology, v. 33, no. 139, p. 99, 1951
 (Miocene, Ecuador).
 Moderately large, rapidly enlarging. Whorls very strongly and sharply carinate at about anterior fourth. Sculpture consisting of 8 or 9 widely spaced spirals. Protoconch of about 1% inflated whorls. Two strong spirals appear on first sculptured whorl: one at middle of whorl, the other halfway between it and anterior suture. A low narrow spiral adjoining anterior suture also appears on first sculptured whorl. Anterior of the two strong spirals gradually increasing in size until on about sixth sculptured whorl it is stronger than middle spiral and forms the carina. At about same stage weak spirals appear between middle spiral and posterior suture, and elsewhere. On late whorls a spiral adjoins anterior suture and a weaker spiral lies between it and carina. Anterior sutural spiral emerging on base as a strong spiral. Base between this spiral and columellar lip sculptured with weak spirals. Growth-line


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