DESCRIPTIONS OF SPECIES. 131 



* Types. — From collection of T. H. Aldricli in the United States National 

 Museum. 



This is merely a species of Madracis with more crowded and more 

 irregularly shaped calices than in the two other species. 



Genus STYLOPHORA Scbweigger. 



Stylophoua minutissima sp. nov. 



PI. XIII, figs. 13 to 15. 



In the United States National Museum are several small branches of 

 this species, weathered out of a cherty limestone. The best-preserved and 

 the most easily studied branch measured 15.5 mm. in length and 2.5 mm. in 

 diameter. The cross section of the branch is circular. The calices are 

 shallow, and are arranged in regular ascending spirals. Their distance apart 

 is about 1 mm. They are elliptical in shape, the greater diameter 0.7 mm., 

 the smaller 0.5 mm. The margins not at all prominent, only a slight bulg- 

 ing upward of the surface in the calicular region. The coenenchymal surface 

 has suffered corrosion, but certainly is granulate, and may have in places 

 possessed some longitudinal striations. Six stout septa reach the columella; 

 no indications of a second cycle. The six septa in places seem so thickened 

 that they almost close the lower part of the calicular cavity. Four pits, 

 each between a pair of septa in the segment of the calice toward the distal 

 end of the branch; two on each side of a vertical plane through the longer 

 axis of the calice are deej^er than the two pits at the other end of the calice 

 (cf. PI. XIII, fig. 14). The columella is stout. It was not possible to 

 determine Avhether or not dissepiments exist. 



Locality. — Russell Sprfugs, Fllut Rivcr, Georgia. 



Geologic horizon. — Vlcksburgiau stage, Ocala group. 



Type. — United States National Museum. 



Tiiis species has an extremely close resemblance to Styhphora affinis 

 Duncan,^ from the Nivaje shale of San Domingo. The resemblance is 

 especially close to the var. minor. The points of difference are: The calices 

 of St. affinis are circular, while in 5'^. minutissima they are elliptical; between 

 the corallites of *SV. affinis there is on the coenenchyma a distinct raised 

 ridge, while no such ridge exists in St. minutissima. 



' Duncau, Quart. Jour. Geol. Soc. London, Vol. XIX, 1863, pp. 436-437, pi. xvi, fig. 4. 



