GASTROPODS: TROCHIDAE TO TURRITELLIDAE


Not Natica guppyana Toula, Li, Geol. Soc. China Bull., v. 3, p. 266, pl. 6, fig. 46, 1930 (Miocene, Panama Bay; =Natica elenae 6cluz, fide Pilsbry, Acad. Nat. Sci. Phila. Proc., v. 83, p. 432, 1931, Recent, Panama Bay). Large, thick shelled, spire low, whorls strongly inflated and rapidly enlarging. Protoconch of 2% to 2y whorls, apical whorl small. Sculpture of relatively widely spaced retractive axial grooves, parallel to growth lines, extending away from suture and generally ending at or above periphery. On some shells they extend to umbilical region, but not on last half of body whorl of large shells. Umbilicus very wide, umbilical rib rapidly enlarging, ending in a moderately wide callus lobe, the anterior part of which is concave on large shells and strongly excavated on shells of small and medium size. On shells of large and medium size a more or less distinct supplementary rib lies on umbilical rib at its posterior border and may modify outline of callus lobe. Groove in front of umbilical rib and umbilical callus lobe moderately wide on large shells, narrow on others. Parietal callus very thick. Operculum dominated by very wide thick warty central rib. Marginal rib very narrow, denticulate. Several minor ribs, two of which generally are undercut along their inner margin, lie between marginal and central ribs. Outermost minor rib irregularly roughened.
 Height 33.5 mm, diameter 30.5 mm (figured large specimen with short axial grooves). Height 30.5 mm, diameter 29 mm (figured large specimen with axial grooves extending from suture to umbilical region on first half of body whorl).
 Type: Tech. Hochschule, Vienna (temporarily at Geol. Inst., Univ. of Berne, Switzerland).
 Type locality: Presumably Gatun Locks excavation, Canal Zone, middle part of Gatun formation.
 Stigmaflax guppiana is the most widespread and most abundant of the Gatun naticids and was found in the Chageas sandstone at the mouth of Rio Indio. All of the numerous large shells and many of medium size have one or more healed breaks on the body whorl. The more widely spaced axial grooves and the excavated umbilical callus lobe differentiate very young shells from very young shells of Natica stenopa. The sculpture is variable. Shells of large and medium size on which the axial grooves extend to the umbilical region are common only in the ipper part of the Gatun formation in the eastern area. Locality 155c is the only locality in the middle part of that formation where all the specimens collected have grooves extending to the umbilical region. No large shell has grooves extending to the umbilical region on the later half of the body whorl. Though the body whorl of some large shells shows indistinct microscopic spiral lineation, like that on some specimens of Natica canrena, there is no gross


87


spiral sculpture. The supplementary umbilical rib is of variable strength, but is visible on shells of large and medium size.
 Opercula are not rare. They were collected at 11 localities, as many as 10 at a locality. A large shell having the operculum in place (pl. 20, fig. 18) was collected by T. F. Thompson. The only other in place is in a minute shell, which has a height of 1.5 millimeters (locality 147b). Details of opercular sculpture are variable, especially the number of minor ribs. The fine denticles on the very narrow marginal rib are obscure on some large opercula. That the thick callus of the warty central rib conceals flat minor ribs, like those adjoining the central rib on some opercula, is shown by the mergence of such ribs on 2 large opercula, (pl. 20, figs. 13, 18). Toula described a small operculum without realizing that it belongs to a species he had named.
 Forms of Stigmaulax closely related to the Recent Caribbean S. sulcata (Born) are found in Miocene formations in Jamaica, Haiti, the Dominican Republic, Puerto Rico, and Brazil. S. guppiana, however, is not one of them. It lacks gross spiral sculpture and is snore closely allied to the Recent Panamic S. broderipiana (Recluz), as pointed out by Olsson (1932, p. 207). S. broderipiana is smaller and has a less depressed suture. The opercula of the two species are similar, but the central rib of S. broderipiana has a narrow crest. S. elenae (RScluz), also a Recent Panamic species, is another close ally. It also has a less depressed suture and its axial grooves are in general more closely spaced. The single available operculum has a narrower central rib. The color pattern, however, is the most distinctive feature of S. elenae.
 S. goppiana is found in the Gurabo formation of the Dominican Republic. A close ally of S. sulcata also occurs in the Gurabo formation, but not at the same localities. This close ally of S. sulcata was recorded as S. vererugosum (Cossmann) (Woodring, 1928, p. 383) and has been named Natica sulcata gurabensis by Rutsch (1934, p. 52, pl. 2, fig. 10). S. guppiana also occurs in deposits of middle and late Miocene age in Florida. The collection from Shell Bluff on Shoal River (USGS 3742) consists of numerous specimens, all smaller than large shells from the Canal Zone. The collection also includes 3 opercula which agree with opercula of S. guppiana. Two specimens from locality 3742 that have short axial grooves were named Natica guppiana toulana by Gardner. This is the common form in the lower and middle parts of the Gatun formation, and the numerous Gatun collections show gradation in the length of the grooves. The single specimen (height 22 millimeters) from Vaughan Creek (USGS 12046) agrees closely with Gatun shells