GEOLOGY AND PALEONTOLOGY OF CANAL ZONE


identified as the Recent Caribbean form designated C. equestris (Linn6) (Woodring, 1928, p. 375, pl. 30, figs. 1, 2).
 Genus Calyptraea Lamarck
 Lamarck, Soc. Hist. Nat. Paris M6m., p. 78, 1799. Type (monotype): Patella chinensis Linn6, Recent, western
 Europe.
 An unidentified small Calyptraea that has an eccentric apex is represented by poorly preserved specimens from the marine member of the Bohio(?) formation at Vamos Vamos.
 Calyptraea cf. C. aperta (Solander)
 Molds of a relatively large, relatively high-spired Calyptraea from the Gatuncillo formation of Madden basin are comparable to C. aperta, which is widely distributed in the Eocene and Oligocene of western Europe and southeastern United States. (For citation and synonomy see Palmer, 1937, p. 145.) In tropical America C. aperta, or a comparable form, is recorded from the Paleocene of Trinidad and the Eocene of Colombia and Perd.
 Occurrence: Gatuncillo formation (late Eocene), localities 9, 12.

 Calyptraea centralis (Conrad)
Infundibulum centralis Conrad, Am. Jour. Sci., 1st ser., v. 41,
 p. 348, 1841 (Miocene, North Carolina, p. 343). Conrad, Fossils of the Medial Tertiary of the United States, No. 3 (Fossils of the Miocene formation of the United States), p. 80,
 pl. 45, fig. 5, 1845 (Miocene, North Carolina).
Trochita sp. indet., Gabb, Am. Philos. Soc. Trans., v. 15, p. 242,
 1873 (Miocene, Dominican Republic).
?Trochita collinsii Gabb, Acad. Nat. Sci. Phila. Jour., 2d ser.,
 v. 8, p. 342, pl. 44, figs. 11, Ila, 1881 (Miocene, Costa Rica). Calyptraea centralis (Conrad), Dall, Wagner Free Inst. Sci.
 Trans., v. 3, pt. 2, p. 353, 1892 (Miocene to Recent).
 Maury, Acad. Nat. Sci. Phila. Jour., 2d ser., v. 15, p. 100, pl. 13, fig. 6, 1912 (Miocene, Trinidad). Maury, New York Acad. Sci., Scientific Survey of Porto Rico and Virgin Islands, v. 3, pt. 1, p. 48, 1920 (Miocene, Puerto Rico). Pilsbry, Acad. Nat. Sci. Phila. Proc., v. 73, p. 385, 1922 (Miocene, Dominican Republic). Maury, Bull. Am. Paleontology, v. 10, no. 42, p. 243, pl. 43, fig. 2, 1925 (Miocene and Pliocene, Trinidad). Gardner, U. S. Geol. Survey Prof. Paper 142, p. 562, pl. 56, figs. 3-5, 1947 (Miocene, Florida); see this
 publication for other citations.
?Calyptraea cf. centralis (Conrad), Hubbard, N. Y. Acad. Sci.,
 Scientific Survey of Porto Rico and Virgin Islands, v. 3, pt. 2, p. 133, 1920 (Miocene, Puerto Rico). Maury, 1925, Brasil Serv. Geol. Mi. Mon. 4, p. 65, pl. 1, figs. 5, 10, 1925 (Miocene
 Brazil).
 Of medium size, circular in ventral plan, apex central. Protoconch of about 1 strongly inflated, rapidly enlarging whorls. Free edge of platform convex forward; reflected columellar edge not closely appressed, forming a relatively high umbilicuslike opening.


 Maximum diameter 16 mm, height 6 mm (largest specimen).
 Type: Apparently lost.
 Type locality: Natural Well, N. Car., Duplin formation (late Miocene).
 Specimens from the Culebra formation, identified as Calyplraea cf. C. centralis, are comparable in size and outline to C. centralis, but none shows the interior. All are molds, with the exception of one, which was collected at locality 108c and has much of the shell preserved.
 The description is based on specimens from the lower part of the Gatun formation. The only large specimen, from locality 138, is imperfect. The interior of the only specimen from the middle part of the Gatun formation is inacessible. It is listed as Calyptraea cf. C. centralis.
 The Gatun fossils that show the interior agree closely with topotypes of C. centralis collected at Natural Well, N. Car. As pointed out by Dall and Gardner, Recent specimens are smaller than those from the Miocene. Recent specimens in the collection of the U. S. National Museum, representing localities from Cape Hatteras to the West Indies, are not more than a third the size of large Miocene fossils. Two large Recent shells, however, are exceptions. One, which has a maximum diameter of 11.5 millimeters, was cataloged at an early date and is labelled "West Indies." The other (maximum diameter 15.5 millimeters) was in the Henderson collection and is labelled "Marco, Florida." The reflected edge of the platform of both is closely appressed, like that of the western European C. chinensis, the type of the genus. They probably are specimens of that species with erroneous locality data. Should a name be desirable for the small Recent race, it may be designated Calyptraea centralis candeana (d'Orbigny), as indicated by Dall's synonymy. Pliocene fossils from the Caloosahatchee marl of Florida have a maximum diameter of 10 millimeters and therefore are intermediate in size.
 The Recent Panamic C. mamillaris Broderip is larger than C. centralis, and has a thicker shell and mottled brown color pattern.
 Occurrence: Culebra formation (early Miocene; Calyptraea cf. C. centralss, Gaillard Cut, localities 99b, 99c, 100, 108c, 11Oa. Lower and middle parts of Gatun formation (middle Miocene); lower part, localities 137, 138, 138a; middle part, eastern area, locality 147j, (Calyptraea cf. C. centralis). Early Miocene, Puerto Rico, ?Costa Rica, ?Brazil. Late Miocene(?), Trinidad. Miocene, Dominican Republic. Early to late Miocene, Maryland to Florida. Pliocene, Trinidad, Florida. Recent (small race) Cape Hatteras to West Indies.
 Genus Trochita Schumacher
Schumacher, Essai d'un nouveau systeme des habitations des vers testacas, p. 57, 184, 1817.


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