July U, 1902.] 



SCIENCE. 



69 



but perhaps not found in the immediate 

 vicinity of the coast. It seems to be strictly 

 confined to the Columbia sands, and is most 

 abundant where this formation is thickest and 

 driest. Frodichia Floridana, a plant nearly 

 as conspicuous but less abundant, seems to 

 have a similar distribution in the coastal 

 plain, though the same or a closely related 

 species is found also on the plains of the 

 Middle "West. 



Other species occurring in Georgia, appar- 

 ently confined to the Columbia formation 

 (with or without Lafayette beneath it), and 

 large enough to be recognized from a moving 

 train, are Actinospermum, angustifolium, 

 Asclepias humistrata, Baptisia perfoliata, 

 Ghrysobalanus ohlongifoliiis, Clinopodium 

 coccineum, Groton argyranthemus, Dicerandra 

 linearifolia, D. odoratissima, Kuhnistera pin- 

 naia, Nolina Georgiana, Paronychia hernia- 

 rioides, Sarracenia flava, and Serenoa serru- 

 lata, besides a host of smaller species. Sarra- 

 cenia flava (the yellow jsitcher-plant), like a 

 few others, is occasionally found outside of tlie 

 coastal plain, but within that region seems to 

 be confined to the Columbia formation. It is 

 a very conspicuous plant when growing in 

 large colonies, and can be recognized at a 

 considerable distance. The two Dicerandras 

 (belonging to the mint family) can sometimes 

 be recognized by their odors alone, and might 

 therefore be useful in traveling at night. 

 Their flowers are autumnal. 



Berlandiera tomentosa, Oraicegus wstivalis 

 (the well-known ' May-haw ' of Southwest 

 Georgia), Dichromena latifolia, and doubtless 

 several other species, seem to be confined to 

 the Lafayette, with or without a thin overlying 

 layer of Columbia, though this relation is 

 much more difficult to determine than that be- 

 tween the Columbia and it-s vegetation, and the 

 chances of error are consequently greater. 



I do not recall at present any species which 

 grows only on the exposed surface of the La- 

 fayette, where the Columbia is absent, but 

 there are probably some which are thus re- 

 stricted in habitat. There are, however, quite 

 a number of species in the coastal plain which 

 seem to occur never where the Lafayette is 

 present, but only on the Columbia or on out- 



crops of the older underlying strata. Among 

 these are Bumelia lanuginosa, Dichromena 

 colorata, Erythrina herbacea. Hydrangea quer- 

 cifolia, Melanthera hastata, Taxodium dis- 

 iichum and Yeatesia Icetevirens, not to men- 

 tion a number of species, especially ferns, 

 which grow usually or exclusively on limestone 

 and could not exist on the Lafayette clay. 



Lastly, Oxypolis filiformis and Taxodium, 

 imbricarium, seem to indicate the simultaneous 

 occurrence of both Lafayette and Columba. 



The relations of the two Taxodiums (cy- 

 presses) to the geological formations are more 

 fully discussed in a paper published in the 

 Bulletin of the Torrey Botanical Club for 

 June, 1902 (pp. 383-399). These two trees, to- 

 gether with the herbaceous species in the group 

 first mentioned, are the principal jilants which 

 have been used in my investigations. 



It would be impracticable to give here a 

 detailed account of my observations on the 

 Lafayette and Columbia formations and their 

 distribution in Georgia, but I may do so at 

 another time and place. I will mention, how- 

 ever, that I have already made notes on them 

 in about forty of the seventy counties lying 

 wholly or partly in the coastal plain of Geor- 

 gia, and have found the above-mentioned 

 botanical relations to hold true wherever it 

 has been possible to verify them. The Col- 

 umbia seems to vary little in composition 

 and appearance throughout this region, 

 though differing considerably in thickness 

 and mode of occurrence in different parts 

 of Georgia. The Lafayette, on the other 

 hand, seems to vary more in appearance 

 than in mode of occurrence. The two forma- 

 tions are very distinct in Georgia, however 

 much they may appear to intergrade elsewhere. 

 In many railroad cuts in the southeastern part 

 of the state it is possible to locate the line of 

 contact between them within an inch or two. 



The term Columbia is of course applied 

 here to the superficial layer of light-colored 

 sand which covers so large a part of the pine- 

 barren region, and differs in some respects 

 from this formation as represented at its type- 

 locality; this geographical variation being anal- 

 ogous to that exhibited by so many species of 



