20 PROCEEDINGS OF THE ISTATIONAL MUSEUM vol.73 



Order MALVALES 



Family STERCULIACEAE 



Genus STERCULIA Linnaeus 



STERCULIA WASHBURNII, new species 



Plate 4, Figures 1-7 



Since these leaves are variable and abundant at a single outcrop, 

 I have considered that they represent a single species of Sterculia^ 

 a genus whose leaves are notoriously variable as to form and loba- 

 tion. It may be described as follows : 



Leaves variable in size and form, palmately three to five lobed. 

 Lobes ovate with rounded tips or conical with acute tips. Sinuses 

 openly rounded, shallow or extending about halfway to the base. 

 Base ranging from decurrent to cuneate to truncate, depending on 

 the number and attitude of the lobes, which may be directed obliquely 

 upward or laterally. Petiole long and exceedingly stout, in one 

 specimen preserved for a "length of 3 centimeters. Margins entire. 

 Texture coriaceous. Length ranging from 4 to 8 centimeters. Maxi- 

 mum width ranging from 2.5 to 8 or more centimeters. Primaries 

 three, stout, diverging from the base, or subbasal in some of the 

 forms with a decurrent base, diverging at acute angles. In the five- 

 lobed forms the lateral primaries give off a short distance above their 

 base a stout lateral which runs to the tip of the lower lateral lobe. 

 Secondaries thin, camptodrome. Tertiaries thin, simple and percur- 

 rent, or flexed medianly, or sometimes forked medianly. 



Named for the collector, Chester W. Washburne. This specie,? 

 has the general features of leaves of this genus, which first appear 

 in considerable abundance in mid-Cretaceous floras of various parts 

 of the world. The genus is common in the warmer parts of South 

 America, at the present time ranging southward to the Argentine 

 Mesopotamia (about latitude 30°). A second fossil Argentine species, 

 not unlike but perfectly distinct from Sterculia umshbwnii, has been 

 described from the supposed Santa Cruz beds of Chubut Territory.^" 



Occurrence. — Bluff about II/2 miles south of Mata Amai:illa, upper 

 Rio Chalia, Territory of Santa Cruz. 



Cotypes.— Cat No. 37868, U.S.N.M. 



^ Berry, Edward W., Johns Hopkins Studies in Geology, No. 5, p. 220, pi. 9, figs. 5, 6, 

 1925. 



