COMI'OSITIOX OF THE FLORA. 



77 



Tho thn'o Wilcox spocios of ]>iiliiis coiiipriso a 

 fan palm and two fcatlicr palms. Tlic Cliama'- 

 doivaL-avosrcproscul a small palm \vhos(>niini(>r- 

 (iiis modern allies ai'c cdnlincd to .Vmcrica. 

 Most of its spocics arc found in the liiimid 

 mountainous regions of Central America, 

 thougli it is also present in coastal lloras, as 

 along the Atlantic <'oast of the Isthnuis of 

 Panama. It is not, iiowevei-, a strictly coastal 

 form and is not found in association with thi' 

 typical Wilcox strand liora, for it occurs onl\' 

 in the hasal AVilcox: (Ackcrm;in format ion t of 

 Ciioctaw t'ounty. Miss., and at the hase of the 

 transgressing upper Wilcox deposits in Saline 

 County, Ark. Its rarity and occurrence in 

 basal hc(ls indicat(>s that its area of gi'owih 

 ■was inland and only reached in these two 

 localities by tlw landward migi-ation of (he 

 strand line. The Sahalites, which I have com- 

 paretl with the existing Suliiil pithnilti}. is com- 

 mon everywhere from th(> base to the top of 

 the Wilcox. It is distinctly a coastal type, 

 rather of tlie lagoons, bayous, and estuaries 

 than of the strand. This fact is indicated by 

 the iVagmentary nature of the remains at many 

 localities anil the occurrence of innumerable 

 complete specimens at other localities, as at 

 Oxford, Miss., where the pres(>nce of imios and 

 the local unconformities indicate an estuary. 



The nipa ])alni, found in tlie Ch'cnada forma- 

 tion or up|)cr Wilcox, is cleaily an inhabitant 

 of mudd}' tidal shores, so that it wordd natu- 

 rally be expected in the laminated clays of the 

 iip])er Wilcox. Its singk' modern representa- 

 tive is tolerant of water of coihsiderable saUnit\' 

 and is a member of the mangrove association 

 of the Orient. It shows many points of afhnity 

 with the Pandanacea^ and has never before 

 been found in the Western Hemisphere. Like 

 so many forms which are strictly oriental in 

 the existing llora, such as Ciimamomum, ^\j'to- 

 carpus, and Phoenix, it enjoyed a cosmopolitan 

 range during at least the earlier half of the 

 Tertiary })eriod. 



AratherfuU accoxint of Ni])a, including a map 

 showing its Keceut and Tertiary distribution, 

 has been recently i)id)lish(Hl.' 



The single species of Canna of the Wilcox 

 represents a strictly hygrophilous tyj)e, which 

 is conlined to ^Vmerica in tlie existing llora. 

 It is an inhabitant of estnary and river swam])s 

 near the coast, and that the Wilco.x species 

 inhabited a similar situation is indicat(>(l by 



'Berry, E. W., Am. Jour. Soi., 4lh ser., vol. 37, pp. oT-liO, fig. 1, 1'JU. 



the small area in which it^ is found and its 

 associiition with Sahalites near tlie mouth of u 

 WUco.x riv<'r, which on other gi'ounds is known 

 to have traversed Lafayette County, Miss. 



The order Aralcs (S])athiflora' of Engler) is a 

 distinct and diversified group of monocotyle- 

 dons that com])ris<>s more than a thousand 

 existing species, most of them belonging to 

 the family Aracete. The kindi-cd family. 

 Lc^nmacere, which consists of smaller forms, all 

 aquatic, comprises but few species, which, 

 however, have a vci-y wide distribution. The 

 distinctive features of i\w ])lants comprising 

 thes(> allied groui)s ai-e the differentiation of tlu^ 

 leaves into stalk and blade; th(> netted venation 

 of the blade; certain anatomical differences; 

 and tlie combination of the flowers into u 

 spadix. The floral structure is varied, ranging 

 from 2-merous to 4-merous, peutacyclic, syn- 

 car])ous forms such as Calannis, with its bract- 

 lik(^ spatlie, to the more a])un(lant bisporangi- 

 ate forms with obsolete perianth and a much 

 developed petaloid spathe specialized for 

 entoiiiophily. 



The ^Vi-aceaj are cosmojuililau, but most of 

 th(> forms are found in the Tropics, massed in 

 South America and the southeastern Asiatic 

 region. There is little evidence that the main 

 differentiation of the aroids was not relatively 

 modern, although Pistia is found in the lower 

 beds of the Upper Ci-etaceous of both North 

 Anrerica and Em-ope. The only known Ter- 

 tiary species are a well-marked form in the 

 Grenada formation or upper Wilcox, evidently 

 of estuarine habitat, and a species in th<> 

 overlyiiig Claiborne Eocene. The species in 

 th(^, upper Wilcox represented by a spadix, 

 Araccseites friteli, is comparable with those of 

 the existing wSouth American genera Spathi- 

 ])hylluni and Monstera, and indicates the exist- 

 ence of swamps in the western embaymeut. 



The Dicotyledons, as might be expected, 

 are largely choripetalous forms. There are 

 over 250 species of Clu)ripetalie (.Vrchicldamy- 

 dese) and only 34 species of Gamojx'taliie (Sym- 

 petala'). At the same time th<> representation 

 of Gamopetalte is really much larger than 

 might be exiiected thus early in the Eocene, 

 and many families often thought to be rela- 

 tively more modern are represent(>(l. 



The following ord(>rs of ChoripetaLc are not 

 represented in the Wilcox flora: Casuarinales, 

 Piperah^s, Salicales, Balanopsidales, I^'itneri- 

 ales, Santtdah>s, Sarraccniales, and Ojiuutiah's. 



