Smaller Foraminifera from Gatuncillo formation-Continued [Identifications by H. H. Renz and P. Bermddez] Localities M Cl C111 15 ra n I .2 .0 .0 17 21 24 31 Textulariella sp --_ -- ------------ _Triloculina cf. T. globosa (Hanna and H anna) ----------- ------ _---cf. T. subrotundata (Montagu) .--I'D ----------------------------Uvigerina adelinensis Palmer and Bermddez..--------------------of. U. atwilli Cushman and Simonson ------------------------cf. U. chirana Cushman and Stonecurta Cushman and Jarvis------gardnerae var. nuttalliana Howe and Wallace opissicosaoa Cushinan and Jarvis- opinolosa Coryell and Embich_... cf. U. spinulosa Coryell and Embich ----_ _- - _- ---- _sp _-..---.---.---- Vaginulinopsis mexicanus (Nuttall) - of. V. mexicanus (Nuttall)-.-sp -------- ---- .----.. -_Valvulineria cushmani Coryell and Embich ------------------------gasparensis Bermddez----------Virgulina cf. V. danvillensis Howe and Wallace.-..-. ---.... _. of. V. dibollensis Cushman and Applin---------------------cf. V. advena Cushman pachyheilus Hadley-_ sp -.----_-..----. .- -- I I I I of the pelagic species-with assemblages from other regions where the stratigraphic position and age are fairly well established. It should be mentioned, however, that the boundary between the lower part of the upper Eocene and the upper part of the middle Eocene, on the basis of smaller Foraminifera, is uncertain throughout the Caribbean region. Two main upper Eocene faunal units are represented: an earlier (localities 24, 31, 17, and 35) and a later (locality 21). The earlier unit itself suggests two minor units: the older represented by localities 24 and 31, the younger by localities 17 and 35. The fauras from localities 24, 31, 17, and 35 are characterized by the occurrence of Bulimina jacksonensis (or a related form), Globorotalia centralis, and Hantkenina alabamensis or H. suprasuturalis. They show distinct affinities with faunas of the Jackson group of southeastern United States, the Jicotea member of the Jabaco formation and the San Luis formation of Cuba (Bermddez, 1950, p. 249-258), the Pauji formation of Venezuela (Nuttall, 1935), and the lower part of the Mount Moriah forniation and the Hospital Hill marl in the San Fernando group of Trinidad (Cushman and Renz, 1948). The fauna from locality 21 has upper Eocene and lower Oligocene affinities. It lacks Globorotalia centralis and Hantkenina. The presence of a form related to Bulimina jacksonensis, however, indicates a late Eocene age. This fauna suggests relationship with that of the Consuelo formation of Cuba (Bermddez, 1950, p. 258-262). Larger Foraminifera.-The first Eocene fossils from Panam6 were recorded in 1891, when Douvill wrote that calcareous algae and heterostegine and orbitoid Foraminifera were found in limestone at San Juan in the upper Chagres valley (DouvillS, 1891, p. 498, 499). He thought the fossils to be of Oligocene age. By the time his second note on the age of the beds along and near the canal was published, he recognized that the orbitoid found at San Juan represents the genus Lepidocyclina (DouvillS, 1898, p. 598-599), later named L. chaperi as a tribute to the collector, an engineer of the first French canal company (Lemoine and R. DouvillS, 1904, p. 14). In a still later publication DouvillS reiterated the Oligocene age, as he was not then aware of the presence of Lepidocyclina in the Eocene (DouvillS, 1915, p. 129-130). At that time, however, lie recorded the occurrence of a stellate discocyclinid ("Asterodiscus") in association with Lepidocyclina in another sample of limestone from the upper Ciagres valley. Vaughan (1919b, p. 549, table opposite p. 595) left these strata in the Oligocene, despite Cushman's suggestion (in a footnote to Vaughan's table) that they should be referred to the upper Eocene. San Juan was located on Rio Pequeni and is submerged by Madden Lake. (For location see Reeves and Ross, 1930, pl. 5.) E. R. Lloyd collected at San Juan in 1919 before Madden Dam was built (locality 3 of present report). When this collection was sent to Vaughan in 1926, he found that at its type locality Lepidocyclino chaperi is associated with late Eocene species (Vaughan, 1926). X Barring unknown structural complications and overlaps, localities 24 and 31 represent the lower third of the Gatuncillo formation, localities 17 and 35 the middle third, and locality 21 the upper third. The following comments concerning the five samples were prepared by Messrs. Renz and Bermudez: A considerable number of species and varieties are unidentified, either because they are undescribed or because comparative material was not available. The smaller Foramisifera in the five samples represent various levels in the upper Eocene. The age determinations are based on a correlation of the faunas-with special emphasis on some GEOLOGY 19