GASTROPODS: TROCHIDAE TO TURRITELLIDAE


 Subgenus Dispotaea Say
 Say, Acad. Nat. Sci. Phila. Jour., 1st ser., v. 4, p. 131, 1824. Type (logotype, Olsson and Harbison, Acad. Nat. Sci. Phila.
 Mo:. 8, p. 276, 1953): Calyptraea costata Say, Miocene,
 Maryland.
 After describing Calyptraea grandis, Say remarked that it does not properly belong in the genus Calyptraea and therefore proposed to place it in a new genus Dispotaea. He then assigned two other species to Dispotaea: Dispotaea tubifera, a new Recent species from South America, and his previously described 'Oalyptraea costata (Say, 1820, p. 40; see p. 38 for locality data), a fossil species from Upper Marlborough, Maryland, associated with others now known to be Miocene. The types of these three species evidently are lost. So far as known Dispotaca tubifera has not been recognized. Calyptraea costata has been interpreted in different ways by Dall (1890-1903, pt. 2, p. 349, 1892) and Martin (1904, p. 244, pl. 58, figs. 7a, b). Dall thought it is the strongly costate Crucibulum that occurs in the St. Marys formation of Maryland and assigned it varietal rank under Crucibulum auricula, the type of Crucibulum. According to Martin, it is the weakly costate Crucibulum found in the Calvert formation of Maryland. Martin's interpretation is reasonable in view of the locality cited by Say and in view of Say's statement that the cup is attached by one side to the wall of the shell. At all events Martin's identification is accepted.
 Olsson and Harbison, apparently not realizing that Say assigned the unequivocally identifiable Calyptraea grandis to Dispotaea, recently designated Calyptraea costate as the type of Dispotaea. The cup of Dispotaca is attached by the right side, or part of the right side, to the interior of the shell. The type species has a wide attachment area; Crucibu?um grande has an attachment area of varied width. The Recent Crucibulum striatum (Say) (Nova Scotia to Florida), which has been cited as the type of Dispotata by several authors, has a consistently wide attachment area.

 Crucibulum (Dispotaea) springvaleense Rutsch Plate 19, figures 8-10
?Capulus? gatunensis Toula, K. k. Geol. Reichsanstalt Jahrb.,
 Band 58, p. 692, pl. 25, fig. 1, 1909 (Miocene, Canal Zone).
 Brown and Pilsbry, Acad. Nat. Sci. Phila. Proc., v. 63, p. 360,
 1911 (Toula's record).
Capulus? sp., Toula, K. k. Geol. Reichsanstalt Jahrb., Band 58, p. 692, pl. 25, fig. 2, 1909 (Miocene, Canal Zone). Crucibulum (Dispotaca) gatunense (Toula), Anderson, Calif. Acad. Sci. Proc., 4th ser., v. 18, no. 4, p. 121, pl. 13, figs. 4-6, 1929 (Miocene, Canal Zone, Colombia). Crucibulen? springvaleense Rutsch, Naturf. Gesell. Basel Verhandl., Band 54, p. 138, pl. 4, fig. 8, 1942 (Miocene, Trinidad).


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 Of medium size, circular to elliptical in ventral plan. Protoconch of 1)) to 1Y rapidly enlarging whorls. Shell smooth to a diameter of 3 to 6 mm. Shell at that stage circular and apex central or subeentral. Sculpture consisting of heavy widely spaced radial ribs, the interspaces bearing crude concentric lamellae, or consisting of closely spaced, generally narrower roughened and pitted irregular ribs. Right side of cup widely attached to interior of shell.
 Maximum diameter 19.2 mm, height 11 mm (figured specimen). Maximum diameter 24.5 mm, height 14 mm (largest specimen).
 Type: 518/190 Basel Natural History Museam.
 Type locality: Springvale quarry, Trinidad, Springvale formation (late Miocene).
 Crucibulum springvaleense is widely distributed in the Gatun formation. Though the interior of the Trinidad specimens, on which this species was based, is unknown, the Crucibulum from Panamd is unequivocally identified. Coarsely sculptured specimens have the external characters of a topotype of C. springvaleense kindly forwarded by Dr. Rutsch. Some fossils from PanamA have only regular coarse sculpture, others only irregular generally finer sculpture, and still others, like tle specimen figured, a coesbination of both.
 This species has left no descendants in the Caribbean region. It appears to be allied, however, to the Recent Panamic Crucibulum pectinatum Carpenter, which has fewer ribs than the coarsely sculptured typical form of C. springvaleense. C. pectinatum ranges from the southern part of the Gulf of California to Panama, possibly to Perd.
 It is unlikely that Crucibuluin springvaleense is the species Toula described as Capulus? gatuneesis. At a diameter of 11.5 millimeters, the greatest diameter of the type of Capulus? gatunensis, it should show traces of strong sculpture, if it were the Crucibulun. According to a communication from Dr. Rutsch, who examined the types of Toula's Gatun gastropods, the type of Capulus? gatunensis is an unidentifiable mold retaining parts of the inner shell layer. In the text Toula cited figures 1 and 2 of plate 25 for Capulus? gatsnensis. According to the explanation of the plate and the dimensions, leowever, figure 2 is his Capulus? sp. Figure 2 quite certainly represents a mold of the coarsely sculptured Crucibulmn that occurs in the Gatun formation. Perhaps through this error in citation Anderson was led to use the nanse Crucibulum gatunense for that species.
 Occurrence: Lower, middle, and upper parts of Gatun formation (middle and late Miocene). Lower part, localities 137, 137a, 138, 138a, 139. Middle part, eastern area, localities 146, 147b, 147e, 147f (identifiration doubtful, immature specimens only), 147g,