4 PROCEEDINGS OP THE NATIONAL MUSEUM vol. 76 



I have described one species as follows: 



D. {Aster ocydina) chipolensis Vatjghan, Fla. Geol. Survey 19th Ann. Rept., 

 p. 161, pi. 1, figs. 6, 7, pi. 2, figs. 8, 9, 1928. Upper Eocene Ocala lime- 

 stone, Bainbridge, Georgia. 



Present knowledge of the stratigraphic distribution of the subgenera 

 of Discocyclina in the Eocene in America may be tabulated as follows: 



Lower Middle Upper 



Discocyclina XXX 



Aktinocyclina X 



A ster ocydina _ X 



The peculiarities of two of the lower Eocene, supposedly Chicon- 

 tepec, species have been pointed out on a preceding page. 



SYNOPSIS OF MEXICAN SPECIES OF DISCOCYCLINA 



The following table may be of assistance in identifying the different 

 species, but it does not include sufficient detail for the discrimination 

 between the species here described and some species described in 

 previous papers. Such detail is given in the text that follows the 

 table. 



SYNOPTIC TABLE OF MEXICAN SPECIES OF DISCOCYCLINA 



Test small, less than 4 mm. in diameter. 

 Shape lenticular. 



Second embryonic chamber embracing the first. 

 Lateral chambers, tiers definite. 



Diameter 2 to 3 times the thickness D. weaveri. 



4 to 5 times the thickness. 



D. weaveri var. parvipapillata. 

 Second embryonic reniform. 



Lateral chambers, tiers definite. 



Diameter 4 to 7 times the thickness D, cristensis. 



Lateral chambers, tiers indefinite. 



Diameter about 10 times the thickness D. perpusilla. 



Test 4.5 to 10 mm. in diameter. 

 Test umbonate. 



Diameter about 5 mm D. cushmani. 



Test not umbonate. 

 Shape lenticular. 



Diameter 5 to 6 mm., usually 5 to 6 times the thickness. 



D. zaragosensis. 

 Shape lenticular or slightly undulate. 



Diameter 6.5 to 10 mm., nearly 20 times the thickness.. D. cloptoni. 

 Shape undulate to selliform. 



Diameter about 5 mm., about 10 time the thickness. 



Lateral chambers with definite boundaries D. stephensoni. 



Diameter about 10 mm., about 10 times the thickness. 

 Lateral chambers without definite boundaries. 



D. palenquensis. 



