Early Paleogene brackish-water molluscs from the Caballas Formation of the East Pisco Basin (Southern Peru) Author DeVries, Thomas J. text Journal of Natural History 2019 2018-12-17 53 25 1533 1584 journal article 24019 10.1080/00222933.2018.1524032 034ebcd9-efa7-416a-822c-b6aee0e57a1c 1464-5262 3670229 Ampullina ortoni Gabb, 1870 ( Figure 4 (g)) Ampullina ortoni Gabb 1870 , 5: 27. Euspira ortoni Gabb 1877 , 264, pl. 35, fig. 3. Ampullina paytensis Woods 1922 , 77, pl. 7, figs. 3, 4. Ampullina ortoni Gabb. Olsson 1928 , 107. Remarks The deep sutural groove on the ampullinid specimen from the Caballas Formation is a diagenetic artefact created by shell material dissolving from between gypsum-filled internal moulds of successive whorls. Thus, the Caballas specimen is not an example of the deeply grooved Ampullinopsis Conrad, 1865 , which is considered by MacNeil and Dockery (1984) to have an exclusively Oligocene record in Europe and the Americas. The specimen of Ampullina ortoni has a thin shell, appressed sutures, and no surface spiral sculpture, contrasting in the last named character with the spirally lined Ampullina gabbi Woods, 1922 , from the Salina Group of Gonzáles (1976) . Olsson (1944) described three new species of Ampullina from the late Campanian beds of the Tortuga Formation in the Sechura Basin of northern Peru : A. breccia Olsson, 1944 , A. tortuga Olsson, 1944 , and A. cumara Olsson, 1944 . The moderately high spire, non-sinuate columella, and elongate elliptical aperture of the Caballas Formation example of A. ortoni most resemble comparable features in A. breccia . Ampullina breccia , however, like the Eocene A. gabbi , has faint spiral threads, which the specimen of A. ortoni lacks, judging from an inspection of a well-preserved external mould from the Caballas Formation. Material UWBM 107627, mostly an internal mould, B8772, L (36.8), W (33.7). Occurrence Upper lower Eocene, Chacra Formation, and middle Eocene, Talara Formation, Talara Basin, northern Peru ; Lower Paleogene, Cuenca Member, Caballas Formation, East Pisco Basin, southern Peru .