GEOLOGY AND PALEONTOLOGY OF CANAL ZONE


 Type: British Mus. (Nat. Hist.), Geol. Dept., Geol. Soc. London 12842.
 Type locality: Dominican Republic, Miocene.
 An incomplete Xenophora, found by T. F. Thompson in the upper part of the Gatun formation at Stanford University locality 2654 near Fort Davis, is referred to X. delecta. The attached shells and shell fragments with one exception (a fragment of the body whorl of a Phos-like gastropod, attached by the exterior surface) consist of pelecypods, Aequipecten being most abundant. These pelecypods and pelecypod fragments are concave side upward, also with one exception: a fragment of a mature Aequipecten scissuratus.
 The generally open umbilicus and relatively strong sculpture differentiate X. delecta from the only Recent species in the Caribbean region, X. conchyliophora (Born). The Gatun fossil is widely umbilicate. On specimens of comparable size from the Dominican Republic the umbilicus is narrower and even reduced to a narrow groove. Rutsch's illustration of a specimen from the late Miocene Punta Gavilin formation of Venezuela also shows only a narrow groove.
 The type of X. delecta is a small specimen, like specimens from the Gurabo formation in the collections of the U. S. National Museum (maximum diameter 24 mm). Two imperfect shells from the Cercado formation are even smaller. The Bowden formation of Jamaica also has yielded only small specimens (maximum diameter 19 mm). The ripples on the base of these small specimens, from both the Dominican Republic and Jamaica, are so strong that they form nodes. Pilsbry figured two large specimens (diameter 51 and 56 mm) that are in Gabb's collection of fossils from the Dominican Republic, and Maury illustrated, under the name X. conchyliophora, a large specimen from the Gurabo formation.
 X. textilina Dall (Gardner, 1926-47, p. 561, pl. 58, figs. 31, 32, 1947), of the Chipola formation of Florida, evidently is an early form of X. delecta. It is umbilicate, but its sculpture is not as strong as that of X. delecta. The larger of the two syntypes figured by Gardner is herewith designated the lectotype. The widely umbilicate strongly sculptured fragment from the Shoal River formation, doubtfully recorded as X. textilina, is indistinguishable from X. delecta. It might, however, be the high-spired subspecies of X. delecta, X. delectafloridana Mansfield (1930, p. 121, pl. 18, figs. 5, 6), which occurs in upper Miocene deposits in western Florida.
 X. delecta left no descendents in the Caribbean or Panamic regions. It is closely related, however, to X. senegalensis Fischer, a Recent west African species, and its close Recent Mediterranean ally, X. crispa "K6nig" Bronn, which occurs in rocks of late Miocene and


Pliocene age in Italy. X. delecta has somewhat coarser sculpture than those species.
 The Recent Caribbean X. conchyliophora has a long history in the southeastern states and is one of the few Recent species recognized in the Eocene of that region. The Recent Panamic X. robusta Verrill, characterized by the deep orange-brown parietal callus and adjoining inner half of the interior of the body whorl, is better, treated as a subspecies of conchyliophora.
 Occurrence: Upper part of Gatun formation (middle Miocene), eastern area, locality 173. Cercado and Gurabo formations (middle Miocene), Dominican Republic. Bowden formation (middle Miocene), Jamaica.' Punta Gavildn formation (late Miocene), Falc6n, Venezuela.
 Family HIPPONICIDAE Genus Hipponix Defrance
Defrance, Jour. Phys. Chim. Hist. Nat. Arts, t. 88, p. 217, 1819. Type (logotype, Gray, Zool. Soc. London Proc., p. 157, 1847):
 Patella cornucopia (Patella cornucopia Lamarck), Eocene, Paris Basin.
 Hipponix species
 The Gatuncillo fossils from the Rio Casaya area include a small presumably immature Hipponix, shaped like a wide cornucopia. Some growth lamellae are' exaggerated and there is a faint suggestion of fine radial sculpture. The muscle scar is not discernible.
 Length (not quite complete) 9 mm, width 7.5 mm, approximate height 6.5 mm.
 So far as this small specimen goes, it suggests a! miniature replica of the type species of the genus.
 Occurrence: Gatuncillo formation (middle Eocene), Rio Casaya area, locality 38.
 Family HIPPONICIDAE?
 Hipponix? species
 A poorly preserved limpet-shaped fossil from the Culebra formation is doubtfully referred to Hipponix. It is moderately large and elongate, and the apex is near the posterior end. The apex is worn and practically smooth. Preserved parts of the outer shell are sculptured with crude radial ribs overriden by crude concentric threads. The interior is inaccessible.
 Approximate dimensions: length 21 mm, width 17 mm, height 9 mm.
 If this fossil is an Hipponix, it is more similar to the Pacific H. pilosus (Deshayes) (an earlier name for H. barbatus Sowerby) than to Caribbean Recent species. H. pilosus ranges from California to Ecuador and the Galapagos, and is found in the western Pacific. It is recorded from the Miocene of the Dominican Republic (Pilsbry, 1922, p. 384).
 Occurrence: Culebra formation (early Miocene), Gaillard Cut, locality 108c.


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