USNM 37505 Betulites rugosus apiculatus Hollick  

Notes

Hollick (1930)

Pl. 36 Fig. 1

 

Locality

From Hollick (1930) (p. 68)

"Yukon River, north bank, about 8 miles below Kaltag (original No. 35); collected by W. W. Atwood and H. M. Eakin in 1907 (lot 4640)."

 

Locality Map

 

Description

From Hollick (1930) (p. 68)

"Leaf orbiculate-ovoid, 6.5 centimeters in length by about the same in width across the middle, denticulate, apiculate at the apex, rounded to a short, truncate base; petiole 1 centimeter or more in length; nervation pinnate, craspedodrome; secondary nerves seven on each side of the midrib, subopposite, parallel, leaving the midrib at angles of about 40°, the upper ones simple, the lower ones branched toward their extremities on the under sides, the basal pair with seven or more branches on the under side."

 

Remarks

From Hollick (1930) (p. 68)

"This well-defined leaf is difficult to differentiate satisfactorily from one or another of the many species and varieties that have been described and figured under the genus Betulites, especially B. westii reniformis Lesquereux (1892) (p. 62, pl. 5, fig. 5) and B. rugosus Lesquereux (1892) (p. 65, pl. 6, figs. 3 - 5) from the Dakota sandstone of Kansas. It hardly appears to be worthy of specific rank, and yet its pronounced apiculate apex serves to distinguish it from the other leaf forms with which it is evidently closely allied. In the circumstances I have thought it best to regard it as a variety of the species which it approaches more nearly in other characters."