1901.] NATURAL SCIENCES OF PHILADELPHIA. 517 



suiting the report of Dr. Smith, where, ou page 109, it is said that 

 Venericardia planlcoda was found by INIr. Aldrich in the upper 

 part of the limestone near Claiborne, which is presumably the 

 orbitoidal part, and this at once proves that it cannot at least be 

 Vicksbmviau. If this is not conclusive, however, it can be sup- 

 plemented by another significant remark, made by Mr. Cunning- 

 ham on page 254 of the same report, to the effect that the orbi- 

 toidal or upper portion of the White Limestone contains large 

 numbers of " minute coralline branches." These are exceedingly 

 abundant in the fauna of the Moody's Branch beds of the Jack- 

 sonian, and constitute one of its conspicuous features, but they are 

 completely unknown from either the lower or upper horizons of the 

 Vicksburgian. 



It is probable that the uplift of the true Vicksburg beds was 

 very limited in geographical extent, and confined to the vicinity 

 of the capes or elbows of the coast separating, on both sides, the 

 Bay of Mississippi from the ocean to the south, and that the 

 so-called Vicksburg localities in eastern Mississippi are to be viewed 

 with suspicion. It will require something more than Dentalium 

 mississipjiiense, Pecten poulsoni and Orbitoides mcmteUi to prove 

 them even approximately synchronous, as these classic species are 

 all noticeably extended in vertical range. 



Mr. D. W. Langdon enumerates^ the fossils collected by him at 

 Byram Station, on the Pearl river. They are all Vicksburgian 

 with the exception of Capulus americanus, which is Jacksonian. 

 As this species has never been found at Vicksburg, the presump- 

 tion is that the Byram beds are older than the true Vicksburg- 

 ian, and this is further borne out by the fact, which I have 

 noted from personal observation, that the Byram deposit con- 

 tains, besides the species quoted by Mr. Langdon, a consider- 

 able number peculiar to it and apparently occurring nowhere 

 else. The evidence adduced by Mr. Langdon would seem to 

 show that there is a notable thickness of marine, though 

 scarcely fossiliferous, deposits between the true Jackson and 

 Byram, and it is probable that during this interval the Red Bluff 



tion which must be considered to be undescribed. In the Lower Claiborne 

 at Natchitoches, Li., another form of Orbitoides occurs, which is smaller 

 and thicker than that of Jackson and Vicksburg and probably specitically 

 different. 



■^ Amer. Jour, ^ci , XXXT, p. 205. 



