﻿DESCRIPTION OF PLATES. 2S3 



Figures 9, ga, and 10. — Williamsonia gigas. Natural molds or casts of ovulate fruits 

 from the cliffs of Hawkser and Runswick, coast of Yorkshire, near Scarborough, together 

 with an artificial cast. 



9. Mold of basal portion of an ortilate strobilus with inprint of sterile organs. A 

 Whitby specimen sent to Brongniart in 1847. 



9<7. An artificial cast made from the preceding natural mold. The cast very clearly 

 displays the true nature of the original strobilus. Compare the receptacle with that of the 

 exactly similar silicified strobilus from the Black Hills shown on plate xi.iu, photograph 5. 



10. Involucre of bracts from cast of interior face of ovulate cone, with part of sterile 

 basal region and globular to conical hollow indicating the form of the receptacle. ( See 

 figures 1 and 4 of the preceding plate.) 



Plate XLVIII. Views from the Southern End of the Cycad Valley, Meade 

 County, Smith Dakota, showing Piedmont-Black Hawk locality in upper 

 cycad horizon of the Eastern Black Hills Rim. 



Photograph 1 — Cycad Hill (1,189 meters), at the southern end of the Cycad Valley, 

 .>'_. miles north of Black Hawk. N. lat. 44° 11' 30"; W. long. 10,3° 19'. Looking south 

 with Fort Benton plains and Pierre hills or Upper Cretaceous Nos. 3 and 4, respectively, 

 in the far distance. Dakota sandstone (Upper Cretaceous No. 1) outcrops at the group of 

 Piiius ponderosa in the left foreground. Wealden sandstones (Jurassic or Lower Cretaceous) 

 form the main foreground and the anticlinal hill to the right yielding various cycadeoidean 

 trunks, as C. ingens, Jenneyana, rhombica, Stilwelli. Over all of the foreground various more 

 or less complete trunks were secured, and at the edge of the thick copse of large pines near 

 the top of the hill (.r) Wieland found many fragments of C. Jenneyana, including a fine 

 summit of a large trunk, this being one of the only two summits of trunks of this species 

 c\er recovered. Over the brow of the hill to the right, and beyond a deep gorge cut well 

 back into the anticlinal, portions of very large and fine columnar trunks were obtained. 

 Much Araucarioxylon wood accompanies the Cycadean trunks. Cycads were first observed 

 at or near this hill in 1877, and a portion of a trunk taken away in that year is included 

 in (he Yale collections. 



Photograph 2. — Cycad Hill, looking south, as indicated by the arrow, into head of 

 ravine mentioned in legend of photograph I. Both in the foreground and amongst the 

 small, thickly set pines to the left of the hill various fragmentary specimens could be obtained 

 formerly, although few or none now remain. Erosion over most or all of the anticlinal sur- 

 face in this view has passed beneath original level of the silicified cycadean trunks, except to 

 I he right of the area seen in the picture, where the cycad horizon passes beneath a talus 

 lining the front of ridge forming the western border of the Cycad Valley. 



Photograph 3. — Looking north. High southeastern border of Cycad Valley, 200 meters 

 east of where C. ingens type was obtained, and about 300 meters northeast of top 

 of Cycad Hill. All the foreground is a fossil cycad landscape or uncovered cycad stratum, 

 and specimens would appear in the photograph just as they originally occurred, had they 

 not been removed. In the distance the northern edge of Cycad Valley appears, as well as 

 the faint outline of the Black Hills, interior to the "Rim." 



Plate XIJX. Views of the Cycad Valley, Eastern Black Hills Rim, South 

 Dakota. Continued from Plate XL/VIII. 



Photograph 1. — Northern slope of the Cycad Hill, looking northeasterly across the 

 outlet of the Cycad Valley, and over its southern and eastern border (ft). The man in 

 the right foreground is at the exact spot wdiere C. ingens type (plate 1) was obtained 



Photograph 2. — The Cycad Valley, looking north from the slope in the extreme right 

 of the preceding photograph, (R) being the same bill. The star in the middle distance 

 denotes the Bear Butte (altitude 1.370 meters), exactly 20 miles north-northwest. The 

 present photograph clearly displays the main features of the Cycad Valley anticlinal. The 

 valley itself has its greatest length of about 2 miles from north to south and is about 1 



