GEOLOGY AND PALEONTOLOGY OF CANAL ZONE


similar to the subgenus Annulicallus Pilsbry and McGinty (1945-50, pt. 4, p. 17, 1946; type (orthotype): Teinostoma carinicallus Pilsbry and McGinty, Recent, Florida). Annulicallus has a sharp ridge at the edge of the umbilical callus, which is concave.
 Teinostoma (Diaerecallus) sychnum Woodring, n. sp.
 Plate 17, figures 28-30
 Small, thick-shelled, periphery rounded. Apical whorl large for size of shell. Very faint microscopic spiral striae visible on penult or earlier whorls of some specimens. Umbilical callus bounded by ridge, which is overlapped by extension of parietal callus. Extension of parietal callus deeply grooved adjoining outer lip.
 Height 1.1 mm, diameter 1.7 mm (type). Height
 1.6 mm, diameter 2.2 mm (largest specimen).
 Type: USNM 561316.
 Type locality: 147b (USGS 6033c, Panama Railroad, about 3,500 ft (1,065 m) southeast of Gatun railroad station, Canal Zone), middle part of Gatun formation.
 The curious callus, shown by four specimens from the type locality, at first glance suggests abnormality. The extension of the parietal callus is formed at a late growth stage. It is missing on three immature shells from the type locality and also on an immature shell from locality 155a, the only specimen from that locality. These immature shells resemble the subgenus Aepystoma, but have a low ridge at the edge of the umbilical callus. The large apical whorl and strongly impressed suture of this species are noteworthy features. No close fossil or living allies are known.
 Occurrence: Middle part of Gatun formation (middle Miocene), eastern area, localities 147b, 155a.
 Genus Anticlimax Pilsbry and McGinty
 Subgenus Anticlimax s.s.
Pilsbry and McGinty, Nautilus, v. 60, p. 12, 1946. Type (logotype (Pilsbry and McGinty, Nautilus, v. 59, p. 77,
 1946) of Climacia Dall, 1903 (not M'Lachlan, 1869), renamed Climacina Aguayo and Borro, 1946 (not Gemmellaro, 1878), renamed Anticlimax): Teinostoma (Climacia) calliglyptumn
 Dall, Pliocene, Florida.
 Perhaps Anticlimax, the second name proposed in rapid succession as replacement of the homonym Climacia, was not intended to be as derisive as it sounds. It recalls some of Jousseaume's names.
 Teinostoma (Climacia) calliglyptum was virtually the monotype of Climacia. Dall used that combination in a list of fossils and in the explanation of a plate (Dall, 1890-1903, pt. 6, p. 1,610, 1,633, 1903). He also used the combination Teinostoma (Climacia) radiata Dall in the same list of fossils. There is, however, no indication that he intended that name for his Collonia


radiata, no matter how unequivocal his intention proves to be.
 The species of Anticlimax have recently been reviewed by Pilsbry and Olsson. The genus is strongly domeshaped and has axial folds or undulations of varying strength on the base of the shell. The subgenus Anticlimax s. s. is characterized by a narrow callus on. the columellar lip, from which a ridge spirals up the widely open umbilicus. The earliest species occurs in the early Miocene Thomonde formation of Haiti. A Recent species is found in the Caribbean Sea and another possibly off Florida, but none so far in thePanamic region.


Anticlimax (Anticlimax) gatunensis Pilsbry and Olsson
 Plate 18, figures 5-7


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Anticlimax gatunensis Pilsbry and Olsson, Bull. Am. Paleontology, v. 33, No. 135, p. 7, pl. 2, figs. 5, 5a, 5b, 1950 (Miocene,
 PananA).
 Dome-shaped, base flattened. Peripheral carina a relatively wide thin ledge. Upper surface sculptured with weak spiral striae, which disappear near periphery and on upper surface of peripheral ledge are replaced by microscopic axial threads. Base bearing 13 heavy axial folds. Outer half of base, including base of peripheral ledge, sculptured with spiral striae. Ridge bordering umbilicus moderately narrow.
 Height 1.7 mm, diameter (incomplete) 3 mm (figured specimen).
 Type: Acad. Nat. Sci. Phila. 18401.
 Type locality: Cut on Boyd-Roosevelt (Transisthmian) Highway, just below bridge over Rio Cativa and about 3% miles from road junction at Margarita,, Panami (same as USGS 16909) lower part of Gatun formation.
 The figured specimen, a topotype, has a damaged peristome and carina. It is the only specimen in the U. S. National Museum collections; two smaller specimens are in the Stanford University collection from the same locality. The flattened base and wide peripheral carina are the most characteristic features of this species. These features distinguish it from the most closely related species, A. schumoi (Vanatta) (1913, p. 24, pl. 2, figs. 2, 7), a Recent species from British Honduras. A. derbyi (Maury) (1917, p. 156, pl. 24, fig. 20), the only other described Miocene species of Anticlimax s.s., occurs in the Cercado formation of the Dominican Republic and in the Thomonde formation of Haiti. It has a more swollen base, narrower peripheral ledge, fewer and heavier folds on the base, and no spiral striae on the base.
 Occurrence: Lower part of Gatun formation (middle Miocene), localities 138, 138a.


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