﻿DESCRIPTION OF PLATES. 269 



Plate XXIII. Surface Features of Cycadeoidean Ovulate Strobili or Cones. 



Photograph I. — Cycadcoidea sp. Surface of seed-bearing region of rather young ovu- 

 late cone enlarged 20 times. (Cf. photograph 5, showing larger area of surface.) 



Photograph 2.—Cycadeoidea dacotensis (T. 61). X 10. Surface of young cone show- 

 ing stigma-like tips of micropylar tubes, each surrounded by from five to six ends of inter- 

 seminal scales in interlocking rosette pattern. 



Photograph 3. — Cycadeoidea sp. X 4- Surface view of a young strobilus quite similar 

 to that seen in photograph 5. 



Photograph 4. — Cycadeoidea Wielandi Ward. X 4- Surface view from near summit 

 of nearly full-sized cone borne by T. 77 and photographed in natural position on the trunk. 



Photograph 5.— Same as photograph 1. X 5- [Number of specimen should be 750.] 



Photograph 6. — C. Wielandi. X 4- Longitudinal thin section through a cone relatively 

 larger, but otherwise of quite similar structure to that shown in surface view in figure 4. 

 This supplementary figure indicates the more usual type of cone preservation in which the 

 nail-head-like ends of the interseminal scales are mostly broken away, thus obliterating the 

 true surface sculpturing and leaving behind only the projecting blunter ends of the more or 

 less distinctly ranked seeds. 



Photograph 7. — Williamsonia Lcckenbyi Nath. Enlarged view of portion of surface, 

 showing the tips of the micropylar tubes projecting between the ends of the interseminal 

 scales in identically the same manner as in the Black Hills specimens, and as in cone impres- 

 sions of Anomozamites from the Trias (103). 



Plate XXIV. Ovulate Strobili of Cycadeoidea. 



Photographs of longitudinal sections through various cycadeoidean ovulate strobili. 

 [That more than a single species is indicated by these several strobili and the trunks from 

 which they are derived is open to question.] 



Photograph 1— Cycadeoidea Wielandi (T. 131). S. 416. X 2.5. (Strobilus and re- 

 ceptacle only.) 



Photograph 2.—C. turrita (T. 364). S. 113. X 2. Strobilus and receptacle with 

 shoulder of old tissue (s), probably marking the insertion of an earlier matured and shed 

 staminate disk. Such a shoulder with a more or less distinct annular band of periderm (?) 

 beneath, extending round the peduncle, hypogynously to the ovulate cone, is present in all 

 these sections, the presumption being that most of these axes, if not all, bore and matured 

 hypogynous staminate disks previous to fossilization. (Cf. enlarged view of basal area 

 (s), plate xxi, photomicrograph 2; also photograph 7, plate xliii, showing a younger cone 

 with synangia and disk remnants still present.) 



Photograph 3.—C. Wielandi (T. 393). S. 391. X 2. Radial longitudinal section of 

 trunk, cutting lengthwise through an ovulate bract-surrounded strobilus borne on a heavy 

 peduncle, between two old leaf bases. Note that the present and two following cones are 

 all from the same trunk. (Cf. restoration, figure 56.) 



Photograph 4.— C. Wielandi (T. 393). S. 392. Natural size. Radial longitudinal sec- 

 tion of trunk, cutting through a strobilus and its peduncle, also through the cortex (<:), 

 xylem (x), and medulla (m), interiorly. This section shows with diagrammatic clearness 

 the direct course of the cortical bundle traces from the xylem cylinder of the trunk into the 

 leaf and peduncle bases. (Cf. outline drawing of same, text-figure 59.) 



Photograph 5.— C. Wielandi (T. 393). S. 218. X 2. Similar to preceding, but with 

 apex of cone entire. 



Photograph 6.— Cycadeoidea Paynei (T. 272). S. 386. X 2. A strobilus similar to the 

 preceding, but with relatively much larger bracts, slender in the basal and robust in the 

 apical region. 



Photograph 7.— Cycadeoidea McBridei. Basal region of a markedly symmetrical 

 strobilus. 



