﻿484 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



slightly elevated, not quite 0.5 mm., due to the projection of the 

 corallite walls beyond the coenenchymal surface. Distinct costae 

 correspond to most, if not all, of the septa; irregular in size, but 

 those corresponding to the primaries are usually the larger. 



Septa in two complete cycles, with a variable number of terti- 

 aries. Primaries usually well differentiated from the other septa, 

 thicker, longer, and somewhat taller; in many calices a larger 

 primary marks the plane of symmetry; secondaries and tertiaries 

 small. 



Columella poorly developed, in some calices a false columella 

 formed by the fusion of the inner end of the primary septa is 

 recognizable. 



Coenenchyma with a flattish surface between corallites, vermi- 

 culately costate, with perforations between the costae in areas not 

 covered by glassy-looking basal deposit, which in the cross-sections 

 of some branches is solid, in the cross-sections of others there are 

 platforms one above another. 



Locality and geologic occurrence. — Canal Zone, stations 6015 and 

 6016, in the Emperador limestone, quarries, in the town of Empire, 

 collected by T. W. Vaughan and D. F. MacDonald. The same or a 

 very closely related species occurs at stations 3381 and 3383, 

 respectively, 4 and 7 miles below Bainbridge, Georgia, in the base 

 of the Chattahoochee formation, collected by T. W. Vaughan. 



Cotypes.— No. 325036, U.S.N.M. (2 specimens). 



Paratypes.~No. 325043, U.S.N.M. (4 specimens). 



ASTREOPORA ANTIGUENSIS, new species. 



Plate 139, figs. 3, 3a; plate 140, fig. 1. 



Corallum forming large thick branches that may be more or less 

 palmate. Plate 139, figure 3, represents a branch one-half natural 

 size. 



The calices are moderately deep, more or less irregular in outline, 

 often subelliptical, the diameter ranges from 2 to 4 mm. Their 

 margins elevated about 1 mm., and are distant from one another 

 from 1.5 to 2.5 mm. Somewhat swollen around the base. Free 

 limbs of corallites more or less distinctl}^ costate. 



The septal arrangement appears often to be irregular, sometimes 

 two complete cycles and an incomplete third, in many calices the 

 third cycle is complete, and occasionally a few members of the 

 fourth cycle may be present. The absence of the smallest septa 

 undoubtedly is often due to their destruction in fossilization. 



Columella very poorly developed, in fact there may be none at all. 



Coenenchymal surface usually formed by a compact basal deposit, 

 but in places perforations may be recognized between costae. 



