98 MESOZOIC FLORAS OF UNITED STATES. 



thick, for it leaves a film of coal, and the lateral nerves of the segments 

 are usually hidden. The axis of the leaf is quite strong and rigid in 

 proportion to the dimensions of the segments or leaflets. The leaflets 

 on different leaves in the same positions vary a good deal in length 

 and width and in the proportion of length to width. They are, as 

 stated, always shorter toward the ends of the leaves, and toward the 

 base are often proportionally wider. Sometimes in that position they 

 are markedly irregular in form, the width being abnormallj^ great. In 

 describing the leaflets we must take the average of more common forms 

 found toward the central portions of the leaves. The leaflets are at- 

 tached nearly or quite at a right angle, by their entire bases, which 

 are of the same width as the main portion of the leaflet. They are 

 linear with parallel sides. The attachment is to the sides of the midrib 

 or axis of the leaf. They are slightly falcate, but may be straight. 

 The tip is obtuse and rounded off, but narrowed somewhat b)' the pos- 

 terior margin curving forward. The nerves of the leaflets are few in 

 number, 5-7, and slender, being generally not visible without the help 

 of a lens. They are attached at the same angle as the leaflets, and 

 are parallel to one another and to the margins of the leaflets. They 

 are not forked, and are of equal strength from their insertions to their 

 ends. The average leaflets are about 8 mm. long and 2 mm. wide. 

 They may, however, be only 3 mm. long and 1 mm. wide. 



The plant has in the form of the leaflets a resemblance to the two 

 fossils figured by Lindlej^ and Hutton as Pteroiphyllum pecten (Phill,) 

 L. & H." and Zamia taxina L. & H.*" It resembles the latter more closely, 

 but the leaflets are mostly smaller and closer. It has the leaflets much 

 closer than the former. 



PL XIX, Fig. 1, gives the largest fragment seen. It shows well the 

 increase in the length of the leaflets in ascending from the base, and the 

 greater width of the basal ones. Fig. 2 gives a fragment of the middle 

 portion of a leaf having average leaflets, and Fig. 3 shows a portion of 

 this enlarged. Fig. 4 represents a fragment from a similar part of the 

 leaf, with narrower leaflets. Fig. 5 gives a basal portion of a small leaf. 

 Fig. 6 shows a fragment of the middle part of a leaf, with wider and 

 shorter leaflets than usual. In these the nerves are rather more remote 

 than is common. They are 5 in number. 



aFoss. Fl. Gt. Brit., Vol. II, pp. 61-62, pi. cii. ^Op. cit., Vol. Ill, p. 67, pi. clxxv. 



