272 TRANSACTIONS OF THE [MAR. 15, 



Millei',* described from the St. Louis group in Kentuck}-. It 

 differs from Miller's species as figured, in the more acute lobes 

 and saddles and in being less globose, though his latest figures 

 represent a shell more compressed than does his original figure 

 and description. 



In none of the specimens studied is the body chamber pre- 

 served, so that the true size of the shells cannot be estimated; 

 but the lai'ger specimens, as preserved, are from one and one- 

 half to two inches in diameter. 



CEUSTACEA. 



Phillipsia sp. 



PI. XXL, fig. n. 



Several imperfect pygidia of a trilobite belonging to the genus 

 Phillipsia are contained in the collection. The specimens are 

 too poorly preserved to admit of specific determination. 



Part III. Correlation. 

 Palkontologic Cokeelation. 



Fossil evidence of the age of the Batesville Sandstone. 



In this section of the paper each of the species recorded from 

 the Batesville Sandstone will be considered separately, and 

 whatever evidence it affords, if any at all, as to the age of the 

 formation will be discussed. 



L Orbiculoidea batesvillensis. 



The members of this genus have a wide range in time, and as 

 the specific characters are generally more or less obscure the 

 occurrence of an undescribed species in the fauna signifies little 

 or nothing as to its age. 



2. Streptorhynchus loilliamsi. 



In the genus Streptorhynchus, as restricted, but a single 

 American species has been recorded, S. ulrichi, from the Kas- 

 kaskia Group in Kentucky. The evidence afforded by the 

 present species is, therefore, in favor of the Kaskaskia age of 

 the Batesville Sandstone. 



3. Productus cestriensis. 

 This species is one of the most characteric of Kaskaskia fossils 



«N. A. Geol. and Pal., p. 439, 440, fig. 740, and BuU. No. 11, 111. State Mus. Nat. Hist.' 

 p. 40, PI 5, fig. 1. 



