80 Cincinnati Society of Xatural History. 



fro7is, -ZV. percequalis, Leda longifrons, now JSfuculana longifrons, 

 Venilia trapezoidea, now Veniella trapezoidea^ (Jardium eufaulense^ 

 Dione eufaule7isis^ Asta^^te crenalirata^ Corhula evfaiilensis, Plica- 

 tula saffordi, P. tetrica^ Pecten a7^gillensis, P. mississippiensis, P. 

 simjylicius, now Syncyclonema simj^licium, Turrilites spiniferus, An- 

 chura ahrupta, Turritella trilira, Daphnella eufaulensis, D. lintea, D. 

 siibjilosa, Drillia distans, Fiisus tippanus, Strepsidura ripleyana^ 

 Volutilithes eufaulensis^ Actceon modicellus, Chemnitzia corona, C. me- 

 lanopsis, C. spillmani, C. laqueata, C. trigemmata, Pyroj^sis perlata^ 

 Keritella densata, Gyrodes alveatus, G. ci'enatus, Turhinopsis hilgardi. 

 Tuba bella, now Spironema bellum, Morea cancellaria, Thylacus cre- 

 taceus, Placunanomia saffordi^ Cassidulus abruptus.^ and C. subquad- 

 ratus. 



Prof. E. W. Hilgard* subdivided the Cretaceous rocks of Mississippi 

 into four groups as follows : 1. The lowest, the Eutaw Group, as char- 

 acterized by Tuomey, near Eutaw, Alabama. 2. Tombigbee Sand 

 Group. 3. Rotten Limestone Group. 4. Ripley Group of Conrad. 



The Eutaw Group consists of bluish black, or reddish, laminated ' 

 clays, often lignitic^ alternating with, and usually overlaid by non-effer. 

 vescent sands, mostly poor in mica, and of a gray or yellow tint. It 

 contains beds of lignite, and rarely other fossils. It is displayed at 

 a few places in Tishamingo, Itaw^amba, Monroe, and Lowndes 

 counties. 



The Tombigbee Group is usuall}^ a fine-grained micaceous sand 

 more or less calcareous, usually of a greenish tint, but not unfrequently 

 gray, bluish, black, j-ellowish and sometimes even orange red. The 

 greenish tint is imparted to these sands not b}' greensand grains, as is 

 the case in the marls of the Ripley ^^roup, but is caused by a greenish 

 incrustation, covering thinl}^ a portion of the quartz grains, but the 

 presence of glauconite in the incrustation has not been detected. 

 Claj's and non-calcareous sands are subordinate to the greenish sand. 

 This Group forms a narrow belt on the western exposure of the Eutaw 

 Group, and extending from Lowndes county through Monroe, Itawamba 

 and Tishamingo, to the southern border of Tennessee. 



The Rotten Limestone Group possesses the same characteristics as- 

 cribed to it by Tuome}^ in Alabama, and appears as a soft, chalky rock, 

 of a white or pale bluish tint, with ver^' little sand; consisting of vari- 

 able proportions of fat, tenacious claj', and white carbonate of lime in 

 cr3'Stals extremely minute, and with some shells of infusoria. It is 



Greo. of Miss. 



