218 



SHORTER CONTRIBUTIONS TO GENERAL. GEOLOGY, 1921. 



sionally widening somewhat medianly and less 

 acutely pointed, separated by generally open 

 and rounded sinuses extending about halfway 

 to the base. The angles that the lobes form 

 with one another and the form of the sinuses 

 vary with the number of lobes, as does also the 

 character of the base, which ranges from trun- 

 cate to decurrent. The median lobe is gen- 

 erally slightly wider than the others but may 

 be smaller. The normal form is five lobed 

 like the smaller of the two specimens from the 

 Cheyenne sandstone here figured. The texture 

 is so coriaceous that these leaves are well pre- 

 served in the scarcely consolidated wind-blowm 

 sand of the Cheyenne. The margins are entire. 

 Length from S to 20 centimeters; maximum 

 .width from 6 to 24 centimeters. Petiole stout, 

 usually broken away, 12 centimeters long in a 

 medium-sized leaf figured by Lesquereux. 

 Midrib stout, channeled, prominent on the 

 under side of the leaf. An equally stout lateral 

 primary diverges from the midrib, usually at 

 its extreme base but occasionally slightly 

 above. In the five-lobed forms this primary 

 forks almost immediately into two subequal 

 branches, which form the midveins of the respec- 

 tive lobes. In specimens having more than five 

 lobes the additional ones are suljordinate to 

 the basal laterals, their midveins diverge at an 

 acute angle from the midveins of these laterals, 

 and their separating sinuses are less deep. The 

 secondaries are thin and immersed in the leaf 

 substance and are largely obsolete in the Chey- 

 enne sandstone specimens; they are numerous, 

 regularly spaced, subparalleled, and campto- 

 drome in the lobes and in curved anastomosing 

 loops in the body of the lamina. 



This is an exceedingly well marked species 

 and, like most Sterculias, both ancient and 

 modern, shows the characteristic variability of 

 the genus. It was described originally from 

 material collected in the Dakota sandstone of 

 Kansas and occurs in the Big Tucumcari 

 Mountains of New Mexico in beds referred to 

 the Dakota. It is recorded from the Magothy 

 formation of Massachusetts and New Jersey. 

 In the Cheyenne sandstone of Kansas it occurs 

 at these localities: Black liills near Belvidere 

 (773); Osage Rock, Belvidere (2217); Stokes 



Hill, 100 yards south of the National Corral 

 (2219); Thompson Creek near the flume, 2 

 miles northwest of Belvidere (2221) ; near 

 Medicine Lodge Creek, 2 miles west of Belvi- 

 dere (2224) ; left bank of middle branch of 

 Champion (Wildcat) Draw, half a mile south 

 of Belvidere (2229); draws north of Belvidere, 

 in "Lanphier shales" (2230); Osage Rock, in 

 "Stokes sandstone" (2232); Wildcat Draw 

 (7405). 



Sterculia mucronata Lesquereux. 



Slerculia mucronata Lesquereux, U. S. Geol. Survey Mon. 

 17 (Flora of the Dakota group), p. 182, pi. 30, figs. 

 1-1, 1892. 



Leaves coriaceous, prevailingly small, pal- 

 matel}' three to five lobed. Lobes entire, conical, 

 separated by open rounded sinuses extending a 

 variable distance, sometimes over halfway to 

 the cuneate or truncate base. Petiole long and 

 stout. Primaries three from the top of the 

 petiole, stout and prominent. In the five- 

 lobed forms subordinate branches from the 

 lateral primaries furnish these with midveins. 

 Secondaries tliin, camptodrone. The tips of 

 the lobes are prominently mucronate, and this 

 feature, which suggested the specific name, is 

 especially obvious in the Cheyenne sandstone 

 specimens, where the mucros are 2 millimeters 

 long and perhaps merit the designation cuspi- 

 date rather than mucronate. 



The fact that these leaves are prevailingly 

 small suggests that they probably represent 

 small leaves of the associated Sterculia towneri, 

 with which they agree in their main features — 

 the mucronate tips of S. mucronata being the 

 principal differential characteristic. The leaves 

 originally described were obtained from tlie 

 Dakota of Ellsworth County, Kans., and the 

 species is known only from that region and the 

 Cheyenne sandstone of southern Kansas, al- 

 though there is a similar but distinct species, 

 Sterculia minima Berry,'' in the Magothy forma- 

 tion of New Jersey and Maryland. Two speci- 

 mens were found in the Cheyenne sandstone 

 near Medicine Lodge River, 2 miles west of 

 Belvidere (2224). 



« Berry, E. W.. Maryland Gcol. Survey, Upper Cretaceous, p. S.57, 

 pi. so, figs. 1-3, 1910. 



