32 



LOWER EOCENE FLORAS OF SOUTHEASTERN NORTH AMERICA. 



water but to the finer sediments then in proc- 

 ess of deposition, which iiflorded a more favor- 

 able habitat to the mud-loving faunas tlian 

 had either the Tuscahoma or Nanafjdia. The 

 Baslu fauna recorded in the available check 

 lists numbers approximately 200 species. Of 

 these species 107, or more than 50 per cent, are 

 peculiar to the formation, 42 of them range 

 both above and below it and so lose their value 

 for close correlations, and of the 42 remaining 

 forms 25 range upward to the Baslii from older 

 beds and 17 range upward into younger de- 

 posits, thus implving that the affinities with 

 the Tuscahoma fauna are closer than with the 

 Hatchetigbee. 



The Hatchetigbee fauna is the most obvi- 

 ously shallow-water fauna recorded from the 

 Wilcox. A few new forms are introduced, 

 which later become prolific, but it chiefly rep- 

 resents the reduced remnant of an earlier life. 

 The capuloids, Trochida?, and NaticidtB are 

 relatively a Uttle more abundant, and Ostrca 

 is represented by 5 species instead of only one 

 or two, as at the earher horizons. The known 

 Hatchetigbee mollusks number approximately 

 84 species, of which 27, or a Uttle less than 

 one-third, seem to be peculiar to the horizon; 

 19 of the remaining forms occur in the over- 

 lying Claiborne group and at some lower hori- 

 zon in the Wilcox; 33 of the 38 remaining 

 species limited in range to the Hatchetigbee 

 are not known from secUments later than the 

 Wilcox, and only 5 of the 38 range from the 

 Hatchetigbee upward into the higher forma- 

 tions of the Eocene. 



West of Mississippi River the studies of 

 Harris and Veatch have demonstrated the 

 presence of marine fossihferous Wilcox in 

 Louisiana and tilong the Texas bank of Sabine 

 River. Harris ' in 1899 listed 16 species of 

 Pelecypoda and 25 species of Gtistropoda 

 from these deposits. Some of the outcrops — 

 for example, those at Marthasville, La., and 

 at Pendleton, Tex. — are regarded by Harris as 

 lower Wilcox ; that at Sabinetown is correlated 

 with the Baslii formation of the Alabama sec- 

 tion. As has already been suggested, the in- 

 sufficient character of the work thus far done 

 on the paleozoology of the Alabama Wilcox 

 makes it impossible to determine the actual 

 range of the species and to what extent their 



recorded occurrences are the result of envi- 

 ronmental conditions and not of chronologic 

 viilue. The rang(> of the forms found west of 

 the Mississippi and the mingling of lower WU- 

 cox or even Midway forms with upper Wilcox 

 forms renders it almost certain that the Ala- 

 bama faunules as at present known are indi- 

 viduiiUy of slight stratigraploic significance. 

 There is thus no satisfactory paleozoologic 

 evidence for cjuestioning the correlations based 

 on the far more satisfactory data furnished by 

 tlie fossQ plants. 



The large area of Wilcox in Mississippi,- Ar- 

 kansas, and Texas, and the deposits of Wilcox 

 age in Temiessee and Kentucky, have not fur- 

 nished any marine fossiliferous outcrops. The 

 absence of animal fossils over tliis vast area has 

 always been a source of wonder. It miglit at 

 least be expected that the remains of insects 

 woidd be found associated with the leaves in 

 the fuie-te.xtured clays, but no remains of tliis 

 sort have been found in any of the Coastal 

 Plain formations earher than the Pleistocene. 

 It is not difficult to account for their great 

 variety in a deposit like that at Florissant, 

 Colo., where the bulk of the sediments are 

 volcanic ash and where solfataric vents existed 

 in the immecUate vicinity of Florissant Lake, 

 but their entire absence in the clays of the 

 Wilcox is certaiidy remarkable. To be sure 

 they may eventually be discovered, but the 

 area of outcrop has now been carefuUy ex- 

 amined over many square miles -nathout suc- 

 cess. The Wilcox flora indicates climatic con- 

 cfitions from which a largo insect fauna can be 

 postulated, as all the insect orders except the 

 Lepidoptera are recorded from pre-Tertiary 

 deposits. 



The following obscure traces of insects are 

 all that the Wilcox deposits have afforded up 

 to the present time. The commonest type of 

 fossil indicating the former presence of insects 

 is fm-iushed by the galleries constructed by the 

 larva? of the TLneidse (Lepidoptera) in the 

 leaves of several species. Th(>se markings are 

 shown on the leaves of the following species: 

 AnoTM ampla, Oarapa eolignitica, Coccolobis 

 eolignitica and C. uviferafolia, Combretum ovalis, 

 DryophyUurn moorei and D. tennesseensis, Ficus 

 scliimpcri and /''. vaughuni, Terminalia Jiilgar- 

 diajM, Zizy phus falcatus and Z. meigsii. (See 



'Harris, G. D., and Veatch, A. C, A prelimiuary report on the 

 geology of lK)uisiana, pp. 290-291, 1899. 



2 A small faunule has recently been discovered in Mississippi by 

 E. N. Lowe. 



