COMPOPITTOX OF T}1E FLORA. 



97 



find S3 species, is confiiiod (o tropical Ainerica. 

 The otiier rathei- luinicrous irihcs arc all repre- 

 sented in more than one continental re;^ion. 



Tlie family contains flie i-('niari<al)le innnl)er 

 of 42 monotypic penera, and thuni^h many of 

 these may be of r(>cent evolution, as a miniher 

 of those from Australia, the isolated occur- 

 rences of many of tiieotli(M-s indicate liuit they 

 are of great age and once occu|)i(-d in((>rvening 

 areas. 



There are oidy l.'l known fossil genera, only 

 about 10 per ceiil (jf the exist ing genera, so t liat 

 little can be said of tlie fossil history (if tiw. 

 family. The oldest genus is ('iti-opliyllum 

 Berry, which is represented by vcvy character- 

 istic leaves with alate petioles in the Dakota 

 sandstone of the Rocky Mountain province 

 and occurs from New Jersey to Alabama along 

 the Atlantic coast in the l{aritan, Magothy, 

 Black Creek (Midtlendorf arkosc member), and 

 Tuscaloosa formations. Another species of 

 Citrophyllum is found in the Wilcox and a 

 third in the overlying Claiborne. Tiiese forms 

 are very similar to the leaves of recent mem- 

 bers of the Aurantioidivc and imdoubtedly 

 represent ancestral forms. The genus Dic- 

 tanmus Linne, which includes a single existing 

 species widely distributed in Eurasia, is repre- 

 sented by a fossil form in the Pliocene of France 

 and another in the Pleistocene of Japan. Lin- 

 ger in 1850 described petrified wood from the 

 Aquitanian of Greece as Klippsteinia medulla- 

 ris, referring it to the AurantioideiB. 



The genus An^\Tis (P. Browne) Linne con- 

 tains about a dozen existing species in the 

 Antilles and Central Ameiica, two of which 

 reach the coast of southern Florida. A fossil 

 foi'm is recorded by Unger from the late Mio- 

 cene (Sarmatian) of LIungary. This determi- 

 nation is not conclusive, however, althougli 

 Unger had both the leaves and fruit of Profa- 

 myns herenices. Unger also descril)ed the su|)- 

 posed ancestral getnis Protamyris, to wliich he 

 referred 4 species from the Acpiitanian of Kunu 

 and the Miocene of Croatia. Tiiese det(>rniina- 

 tions are not especially convincing, and hotii 

 Ettingshausen and Schenk consider rrofami/iis 

 radobojana Unger to reprc-sent a species of 

 Cedrela. 



Tlie genus Xantliox3dum Linne, which in- 

 cludes 9 or 1 existing species of eastern Asia and 

 North America, has been a favorite receptacle 

 for fossil forms of llutacea'. About a score of 



50243°— 16 T 



fossil species have been described. Tlie oldest 

 comes from the basal Eocene of northeastcMii 

 New Mexico (Raton format ion) and a second 

 ICocene species is recorded from tlie Bartonian 

 of France. Engelhardt has described 2 Eocene 

 or Oligocene species fioni Chile. Then^ are 4 

 Oligocene species, 2 in France and 2 in Prussia. 

 Tliei'c ai-e about \'-\ Miocen(> s|)ecies, widely dis- 

 tril)ut('d and represented in ('alifornia, Colo- 

 rado, Spain, I'^rance, .Switzerland, Baden, Bo- 

 liemia, Croatia, and Hungary. The 2 Pliocene 

 species I'cpresenl {''lance and Asia Minor, and 

 one of the Recent species is found in tlie Pleisto- 

 cene of Japan. It seems probable tluit Xan- 

 thoxylum was derived from Fagara tlu'ough a 

 loss of tiie lloi-al calyx and by ada])tatioii to 

 cooler climatic conditions. 



The genus Fagara limie is suljstituted for 

 Xantiioxylum by many n^cent systematists, 

 although I prefer to consider it as the ancestral 

 stock and use it in the older sense, as including 

 the 150 cosmo])olitan tropical species. To 

 Xantiioxylum 1 woidd refer the extratro]>ical 

 forms of Asia and Nortli America. Lindoul)t- 

 edly s(n'eral if not all of the fossil forms de- 

 scribed as species of Xantiioxylum are more 

 jirojierly i-cfcrred to Fagara, althougli none have 

 lieretoforc been described under this name cx- 

 cc])t forms from Florissant, Colo., and from Cali- 

 fornia, which are probably referable to Xanthoxy- 

 luni. The Tertiary flora of southeastern North 

 America contains several very characteristic 

 forms of Fagara. The oldest forms are three 

 species from the Wilcox group. There is 

 another species m the overlying (,'laiborne 

 grouji. Tiie Vickslnirg group has furnisluHl a 

 very common form, which has several well- 

 marked varieties in some of the leaves of whicli 

 the glandular )>unctate character is beautifullv 

 jU'csei'ved. Still another form is found in the 

 Apalaehicola grou]i of Florida. 



The genus Rnta Ijiime, which includes more 

 than 100 existing species, mostly of Eurasia, 

 although found also in Africa and South Amer- 

 ica, is represented by characteristic capsules in 

 the Aquitanian of Rhenish Pnissia, described 

 by Menzel in 191.3, and by 2 species in the 

 Pliocene of Limlnirg described by Reid. 



TIhi genus Pludlodeiidron Ruprocht, which 

 includes 2 existuig Asiatic species, is repre- 

 sented in the Aquitanian of Rhenish Prussia 

 by fruits (drupe) and 3 well-marked s])ecics 

 ure present in the l^liocene of Limburg. Engel- 



