GEOLOGY AND PALEONTOLOGY OE THE CANAL ZONE. 579 



also occurs in the Oligoccno of Antigua, and according to Doctor 

 MacDonald the Bohio underlies the Culebra formation, the lower 

 part of which seems to be of middle Oligoccno age. However, tho 

 Bohio may be of middle Oligoccno instead of lower Oligoccno age. 



Romanes reports from Manzanilla, on the Pacific coast of Costa 

 Rica, 1 a cherty rock in which there are remains of Foraminifora, 

 including Gobigerina and "a complex form allied to Tinoporus," 

 which according to Dr. R. L. Sherlock is "most probably a species of 

 Orbiioides." As the so-called species of Tinoporus from Trinidad, 

 according to Douville, are referable to Or'Jiopliragmina (Asierodiscus) , 

 it appears almost certain that tho "form allied to Tinoporus" 

 mentioned by Romanes is a species of Asierodiscus. Dr. J. A„ 

 Cushman has examined Romanes's figure, 2 based on a photomicro- 

 graph of a thin section of tho rock from Manzanilla, and writes me 

 that it shows " OrtJiophragmina and abundant Globigerina, and that 

 the rock may be similar to that at David and on Haut Chagres." 

 The evidence is not entirely decisive, but the probability is very strong 

 that the rock from Manzanilla, Costa Rica, is of lower Oligoccno 

 (Lattorfian) ago as is that at David and on Haut Chagros. It is 

 unfortunate that the box containing Mr. Romanes's most important 

 specimens was lost in transit, but, notwithstanding this loss, he has 

 made a valuable addition to the literature on tho geology of Costa 

 Rica. 



Hill, in his description of a geologic section from San Jose, Costa 

 Rica, to the coast at Port Limon, says: "At Guallava, tho next 

 station east of Las Animas, the Tertairy rocks are of Vicksburg age, 

 according to Dr. Dall." 3 On page 275 of Hill's paper, Doctor Dall 

 lists from this locality "the genuine Orbiioides manielli, Phos, Denial- 

 Hum, Plicaiula, Anomia, etc., all Vicksburg species." 



Between Costa Rica and Mexico there is no definite evidence as to 

 the presenco or absence of lower Oligocene deposits, but as Sapper 

 mentions Nummuliies from Zacualpa, Yucatan, either Eocene or 

 Oligocene occurs at this place; 4 and, judging from the indefinite 

 statements of Sapper, deposits of cither Eocene or Oligocene ago 

 underlie extensive areas in Chiapas and northern Guatemala. 5 



Felix and Lenk ° report Nummuliies and "Orbiioides" in northern 

 Chiapas, from collections made by Karsten, and refer them to tho 

 Eocono, but sufficient data are not given to decide whether tho 



1 Romanes, J., Geology of a part of Costa Rica, Geol. Soc. London Quart. Journ., vol. 68, pp. 130, 131, 

 pi. 9, fig. 4, 1912. 



s Idem., pi. 9, fig. 4. 



8 Hill, R. T., Tho geologic history of the Isthmus of Panama and portions of Costa Rica, Mus. Comp. 

 Zool. Bull., vol. 28, No. 5, p. 232, 1898. 



4 Sapper, Carlos, La gcographia fisica y la gcologica de la Peninsula de Yucatan, Mexico Inst. geol. Bol. 

 3, p. 7, 1896. 



6 Petermann's Mittheil., Ergiinzungs vol. 27, Erganznngshcft. 127, p. 67, 1899. 



6 Felix, J., and Lenk, H., Leber das Vorkommen von Nummulitenschichten in Mexico, Neues Jahrb. 

 fUr Min. Jahrg. 1895, vol. 2, pp. 208-209, 1895. 



