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GEOLOGY AND PALEONTOLOGY OF CANAL ZONE


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of medium size that have grooves extending to the umbilical region. According to Tucker and Wilson, S. guppiana occurs in upper Miocene deposits at Acline, Florida.
 A large Stigneelax from the late Miocene Punta Gavilln formation of Venezuela has been described as Natica (Stigmaulax) sulcata beaumonti Rutsch (1934, p. 50, pl. 2, figs. 6-8, pl. 3, fig. 5). I am indebted to Dr. Rutsch for two topotypes of this form. It is allied to S. guppiana and may be considered a subspecies of S. guppiana. It is considerably larger than S. guppiana proper (height 42 millimeters), but even on these large shells the axial grooves continue to the umbilical region almost to the outer lip. This large form, S. guppiana beaumonti, and the typical form of S. guppiana in the Chagres sandstone are the last Caribbean allies of S. broderipiana.
 Occurrence: Lower, middle, and upper parts of Gatun formation (middle and late Miocene). Lower part localities 137, 137a, 138, 138a. Middle part, eastern area, localities 142, 146, 147 (identification doubtful), 147b, 147f, 147g, 147h, 150a, 151, 153, 153a, 1551, 155b, 155c, 156, 157, 158 (identification doubtful); western area, localities 161, 161c, 161d. Upper part, eastern area, localities 172, 175, 176, 176a, 177a, 177b, 177c, 178; western area, localities 182, 182a, 183, 185. Chagres sandstone (early Pliocene), locality 208. Miocene, Falc'n, Venezuela. Middle Miocene, Bolivar and Choc6, Colombia. Daule formation (middle Miocene), Ecuador. Middle Miocene, northeastern Panami and Costa Rica. Miocene, Chiapas, Mexico. Shoal River formation (middle Miocene), Florida. Late Miocene deposits at Acline, Florida.
 Genus Tectonatica Sacco
Sacco, Mus. Zoologia Anatomia Comparata R. Univ. Torino Bel., v. 5, no. 86, p. 33, 1890.
Type (monotype): Tectonatica tectula Bors. (error for Bon.)
 (Natica tectula Bonelli), Miocene and Pliocene, Italy.
 Though the name Tectonatica has been used for small tropical American species (Woodring, 1928, p. 384), that usage was not entirely satisfactory, because no specimens of the type species were examined. Through the kindness of John Q. Burch, of Los Angeles, a specimen of Natica tectula identified by Sacco is now available. It is larger than the small tropical American species (height 7 millimeters; maximum height 12 millimeters, according to Sacco) and the umbilical callus lobe does not completely fill the umbilicus, leaving a narrow unfilled space, comparable to the narrower space of varying width on the small American "Natica" pusilla Say. In his later description of Tectonatica. Sacco (1891, p. 81) described the operculum as calcareous. He evidently was relying on allied Recent species, as in his description of Natica tectula the


operculum is not mentioned. Though the operculum of that species evidently is still unknown, there is no reasonable doubt that Tectonatica is an appropriate name for the small American species. The type of Cryptonatica (Dall, 1890-1903, p. 362, 1892; type (logotype, Dall, 1909, p. 85): Natica clause Broderip and Sowerby) is a large arctic and boreal species, on which the umbilical callus lobe completely fills the umbilicus. Like the small species, it has a smooth calcareous operculum. When the anatomy of the large arctic and small tropical species is known, both names (Tectonatica and Cryptonatica) may be found to be useful.
 Tectonatica has been recognized in the Eocene of England (Wrigley, 1949, p. 14).

 Tectonatica species
 Two imperfect specimens record the occurrence of a small inflated species of Tectonatica in the late. Eocene or early Oligocene strata of Trinidad Island. The unbilical callus lobe is preserved on the smaller specimen, but is absent (presumably dissolved) on the larger. The larger specimen has a more strongly bulging body whorl than T. agna of the Gatun formation. T. foridana (Dall) (1890-1903, pt. 2, p. 366, pl. 17, fig. 5, 1892), of the early Miocene Tampa limestone of Florida, is more than three times as large and is more elongate. Heretofore T. foridana was the earliest recorded east American species.
 The larger specimen has the following dimensions: height 2.4 mm, diameter 2.6 mm.
 Occurrence: Marine member of Bohio(?) formation (late Eocene or early Oligocene), Gatun Lake area, locality 42.
 Tectonatica agna Woodring, n. sp.
 Plate 17, figure 46
 Very small, strongly inflated, spire low or moderately low. Protoconch not clearly differentiated from remainder of shell, apical whorl small. Umbilical callus lobe thick, completely filling umbilicus, bearing a shallow central depression. Edge of umbilical callus lobe raised above level of umbilical border. Parietal callus thick. Operculum unknown.
 Height 2.8 mm, diameter 2.4 nn (type).
 Type: USNM 561348; 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.
 This minute Tectonatica, like many other small species from the Gatun formation, is abundant at locality 147b, the type locality. The shallow, but distinct, depression on the umbilical callus lobe is its