ADDITIONS TO THE FLORA OF THE WILCOX GROUP. 



15 



States National Herbarium I found that it 

 was identical with material from Costa Rica 

 which Messrs. Standley and Safford consid- 

 ered to represent a new genus, very probably 

 a member of the Icacinaceae. They have 

 since recognized three species of this genus — 

 two from Mexico and one from Costa Rica and 

 Panama. These are trees of considerable size, 

 with broadly lanceolate camptodrome-veined 

 leaves. The fruits have a thin flesh in life 

 and a single large spherical seed. The fossil 

 form is similar in shape and ornamentation 

 but is only about half the size of the recent 

 fruits and may therefore be considered as 

 standing in an ancestral relation to the modern 

 genus, for which Standley and Safford have 

 proposed the name Calatola. 



The occurrence of a fossil representative of 

 the family Icacinaceae in the lower Eocene of 

 Texas is of very great interest. No member of 

 the family, so far as I know, has ever before 

 been found fossil. The family consists of 

 about 39 genera and 150 existing species, of 

 which only 8 genera, with less than 30 species, 

 are found in America, where they are for the 

 most part- confined to the Tropics. None of 

 these genera except Mappia, a native of the 

 Antilles, occurs in any other geographic region, 

 and this genus is supposed to be represented 

 in Ceylon and farther India. As the forms 

 from farther India constitute the subgenus 

 Trichocrater and those from Ceylon the sub- 

 genus Eumappia, it seems doubtful if Mappia 

 is really an exception to the peculiar character 

 of the existing American members of this 

 family. The family as a whole is distinctly 

 oriental in the existing flora, with its center of 

 dispersal in the south Asian region, for although 

 there is only a single monotypic genus con- 

 fined to southeastern Asia, this region pairs 

 with Africa, the East Indies, or Australia in 

 many occurrences : thus there are 8 genera with 

 23 species which are Malaysian, 6 genera with 

 34 species which are Asian and Malaysian, 

 3 genera with 19 species which are common to 

 Africa and southern Asia, and 1 genus with 4 

 species common to Malaysia and Australia. 

 Ten genera with 33 species are confined to 

 Africa, and 3 genera with 6 species are confined 

 to Australia. 



The family contains 10 monotypic genera — 

 one of Guiana and all the remainder Old World 

 forms, as follows : Africa 3, southeastern Asia 1 , 

 84765°— 22 2 



East Indies 2, New Guinea 1, New Caledonia 2. 

 All the existing American forms belong to the 

 large subfamily Icacinoideae, which is also 

 represented in all the other regions, so that its 

 origin or interrelationships are unknown. 



Occurrence: Butler (West Point) salt dome, 

 in the eastern part of Freestone County, near 

 Trinity River, 6 miles northeast of Oakville, 

 Tex.; collected by O. B. Hopkins and O. C. 

 Funderbimk. 



Order RHAMNALES. 



Family RHAMNACEAE. 



Genus RHAMNTJS Linne. 



Rhamnus cleburni Lesquereux. 



Rhamnus cleburni Lesquereux, IT. S. Geol. and Geog. Sur- 

 vey Terr. Ann. Rept. for 1872, p. 381, 1873; Tertiary 

 flora, p. 280, pi. 53, figs. 1-3, 1878; U. S. Nat. Mus. 

 Proc, vol. 11, p. 24, 1888. 

 Knowlton, U. S. Geol. Survey Bull. 204, p. 80, 1902. 

 Berry, U. S. Geol. Survey Prof. Paper 91, p. 283, 1916. 



The present material, which is abundant, 

 emphasizes the great similarity and possible 

 identity between this form and Rhamnus cou- 

 shatta Berry, 22 also the great variability in out- 

 line of these leaves, many of which are longer 

 and relatively narrower than the type and show 

 indications of grading into what I have called 

 Rhamnus marginatus apiculatus. 23 



Occurrence: Goss pit, half a mile east of 

 Mansfield, De Soto Parish, La.; collected by 

 O. M. Ball. 



Rhamnus marginatus apiculatus Berry. 



Plate XI, figures 2, 3. 



Rhamnus marginatus apiculatus Berry, U. S. Geol. Survey 

 Prof. Paper 91, p. 283, pi. 69, fig. 1, 1916. 



At the time of the publication of the report 

 on the Wilcox flora this variety was represented 

 by a small number of specimens from the Acker- 

 man formation of Mississippi. It is common in 

 later collections from Louisiana and shows con- 

 siderable variation in size and outline. All the 

 specimens are somewhat narrower than the 

 type; some have a very long acumen and others 

 lack a prominent acumen. Two of these speci- 

 mens are figured, the larger a leaf 21 centime- 

 ters in length and 4 centimeters in maximum 

 width. 



22 Berry, E. W., U. S. Geol. Survey Prof. Paper 91, p. 2S4, pi. 68, f 

 191S. 

 "Idem, p. 283, pi. 69, fig. 1. 



