228 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.46. 



more abundantly, while the cerites and melanians are generally dis- 

 tributed. 



This account of the fauna is published by permission of the 

 Director of the United States Geological Survey, under whose 

 auspices the fossils were collected. 



A description of the species found follows : 



RANGIA CUNEATA Gray, var. SOLIDA, new. 

 Plate 20, fig. 7. 



Shell small, very solid, rounded triangular, externally smooth 

 except for incremental lines; beaks low, pointed, close to the margin; 

 dorsal margins nearly straight, meeting under the beaks at an angle; 

 hinge much as in R. cuneata but the laterals shorter. 



Length 20, height 17, diameter 10 mm. 



Station 6040; abundant; also from the locaUty on the Satilla 

 River, Georgia. Type, U. S. Nat. Mus., No. 166282. 



This form differs from R. cuneata in many particulars; if the speci- 

 mens collected are adult, there is an enormous difference in size; but 

 of this I am uncertain and so lay no stress on this feature. Specimens 

 of R. cuneata of the same size as the fossils differ by being more 

 inflated and less triangular; by having the beaks more distant from 

 the hinge line and the dorsal margins constituting one sweeping 

 curve instead of meeting at an angle; by the longer and more sharply 

 striated lateral teeth and larger cardinals. 



This is the form referred to in Aldrich's list. 



MULINIA SAPOTILLA Dall. 



Plate 20, fig. 1. 



Mulinia sapotilla Dall, Trans. Wagner Inst., vol. 3, pt. 4, p. 902, pi. 28, figs. 7, 

 8, 9, 14, 1898. 



Stations 6040 and 6445. Also in the Pliocene of the Caloosahat- 

 chie River, Florida, as one of the most characteristic species. 



The specimens from the Satilla mari are all immature and vary 

 very much in relative length, inflation, etc. I have seen no other 

 Mulinia from these marls and feel reasonably confident that the M. 

 congesta mentioned by Mr. Aldrich is an accidental intruder. M. 

 lateralis might well occur here, but has not been found in any of the 

 material I have examined. 



HETERODONAX ALEXANDRA, new species. 

 Plate 20, fig. 8. 



Shell differing from the recent H. himaculata in the different pro- 

 portions of the valves before and behind the beaks, the anterior 

 portion being shorter and the posterior portion much more produced 

 and more compressed. The posterior part of the valve is consider- 



