408 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



carefully restudied the specimens, and, as I can find only dissepi- 

 mental endo- and exotheca, they can not be identified as Duncan's 

 Astraea tenuis. Because of silification and changes due to fossiliza- 

 tion the columellar characters are obscured, but it is possible to 

 recognize the presence of a lamellar columella. The species, there- 

 fore, is definitely Antiguastrea cellulosa (Duncan). 



ANTIGUASTREA CELLULOSA var. CURVATA (Duncan) 



Plate 98, figs. 4, 4a. 



1863. Astraea cellulosa var. curvata Duncan, Geol. Soc. London Quart. Joum., 

 vol. 19, p. 418. 



Original description. — "Corallites slender, long, close, sometimes 

 compressed; circular in transverse section, except when compressed. 

 Walls thin and delicate. Costae delicate, unequal, narrow at the 

 base, tapering externally. Septa well developed, in six systems of 

 four complete cycles. The primary septa are large, toothed on either 

 side, not larger at any one point than at another. The secondary 

 septa are smaller than the primary, and have a tooth near the 

 columella. The tertiary are smaller than the secondary, vary much 

 in size, often extend nearly up to the columella, and curve there 

 towards the latter; they have lateral teeth, and a larger tooth at the 

 end; or they reach only haKway, being either straight or curved. 

 The quaternary septa have wedge-shaped bases and spike-hke pro- 

 longations, extend one-quarter the distance to the columella, and 

 sometimes curve towards the tertiary. Columella lax and parietal. 

 Endotheca greatly developed, subdividing the septal loculi by 

 transverse bars. Exotheca distinct, cells small. 



"Dimensions. — Diameter of the corallites one-fifth inch [5 mm.]; a 

 bud 1 line [2 mm.] in diameter has three cycles. 



"Chert-formation of Antugua. Coll. Geol. Soc. As a rule, this 

 variety is curiously fossihzed." 



Plesiotype.—U.S.^.M. No. 324923 (pi. 98, fig. 4, 4a). This is 

 actually more abundant in Antigua than the typical examples of the 

 species. I doubt the presence of teeth on the primary and secondary 

 septa. The appearance of their being present is probably due to 

 changes resulting from fossHization. 



ANTIGUASTREA CELLULOSA var. SILICENSIS, new variety. 



Plate 101, figs. 1, la. 



The two distinctive characters of this variety are, (1) the flat or 

 domed upper surface; (2) the rather large calices, which are occa- 

 sionally only 4 mm. in diameter, but usually 5 to 6.5 mm., sometimes 

 the diameter may be as much as 11.5 mm. when the fifth cycle of 

 septa is nearly complete. 



Localities and geologic occurrence. — Basal part of the Chattahoochee 

 formation. Blue Springs, Flint River, 4 miles below Bainbridge, and 



