70 Cretaceous. 



frons, -ZV. x>er(Bqualis, Leda longifrons, now Nxiculana longifrons, 

 Venilia trapezoidea, now Veniella trapezoidea^ Cardium eiifaulense, 

 Dione eufmdensis, Astarte crenalirata^ Corhula eufaidensis, Plica- 

 tula saffordi, P. tetrica, Pecten argillensis, P. mississippiensis, P. 

 simplicius, now Syncyclonema simjyliciuni, Turrilites s]yin.!ferus, An- 

 chura abriqyta, TuryHtella trilira, Daphnella eufaidensis, D. lintea, D. 

 subjilosa, Drillia distans. Fusus tippanus, Strepsidura ripleyana^ 

 Volutilithes eufaidensis, AcUeon modicellus, Chemnitzia corona, C. me 

 lanopsis, C. spillmani, C. laqueata, C trigemmata, Pyropsis perlata, 

 Neritella densata, Gyrodes alveatus, G. crenatus, Turbinopsis hilgardi. 

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

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

 ratus. 



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

 into four gi'oups as follows : 1. The lowest, the Eutaw Group, as char- 

 acterized by Tuomey, n^ar Entaw, 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, Itawamba, Monroe, and Lowndes 

 counties. 



The Tombigbee Group is usually a fine-grained micaceous sand 

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

 gray, bluish, black, yellowish and sometimes even orange red. The 

 greenish tint is imparted to these sands not by greensand grains, as is 

 the case in the marls of the Riple}^ Group, but is caused by a greenish 

 incrustation, covering thinly a portion of the quartz grains, but the 

 presence of glauconite in the incrustation has not been detected. 

 Clays and non-calcai-eous 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, chalk}' rock, 

 of a white or pale bluish tint, with very little sand; consisting of vari- 

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

 crystals extremely minute, and with some shells of infusoria. It is 



Geo. of Miss. 



