JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 91 



be regarded as a variety and called var. minor. The chief difference is 

 in the lateral nerves. 



There is a considerable difference in the size of the type forms. The 

 largest attains a width of 4 cm. The length in no case is shown, as the 

 specimens are all fragments of leaves. The longest fragment has a length 

 of 8 cm. The smallest fragment is only 2 cm. wide. The leaf was appar- 

 ently thin in texture, and the fossils are often found much puckered and 

 lacerated. When the upper surface is presented uppermost, as is generally 

 the case, a cord replaces the midnerve. In this cord the bases of the 

 lateral nerves of the lamina of each side of the midrib are inserted. These 

 nerves are very distinct, slender, and uniform in thickness from base to 

 end. As a rule, their bases are inserted at equal distances, and the nerves 

 go strictly parallel to one another in their course to the margin of the leaf. 

 Usually they are rather remote, being about three for every 2 mm. of 

 interval. They are inserted nearly at a right angle and curve slightly 

 toward the tip of the leaf. Very rarely, and as it were by accident, a 

 nerve forks, and sometimes in the same fashion two adjacent ones go off 

 from the same point of insertion. Such a pair may unite halfway up in 

 the lamina and go to the margin as a single nerve. These features are 

 clearly not essential ; although only fragments of leaves were obtained, 

 their mode of narrowing indicates that they were not long, and were in 

 form elongate-elliptical, obtusely rounded off at their bases and summits. 



PL XVI, Fig. 3, gives, poorly preserved, a fragment which is the 

 longest that was found. Fig. 4 gives with better preservation a some- 

 what wider leaf in a fragment from the middle part. Fig. 5 shows a 

 fragment of a medium-sized leaf from the middle part, only the lamina 

 on one side being preserved, and showing a laceration that imitates 

 original segmentation. Fig. 6 is a small fragment from the middle part of 

 a medium-sized leaf. Fig. 7 gives a fragment from the middle part of one 

 of the smallest leaves, and Fig. 8 a portion of this enlarged. Fig. 9 shows 

 the puckering and laceration that imitates another kind of original 

 segmentation. 



The plant occurs most abundantly at locality No. 18, but is found also 

 at localities Nos. 1, 2, 7, 8, 14, 16, and 17. 



