738 



SCIENCE. 



[N. S. Vol. XXIII. No. 593. 



The conditions prevailing in the petrified 

 forest are interesting and deserving of some- 

 what special notice. The deposits of the 

 Grand Canon region, usually spoken of as a 

 single great group of beds, are reduced by 

 Ward to three entirely distinct formations. 

 The lowest, presenting their full development 

 at the mouth of the Mcencopie Wash, are 

 known as the Mcencopie beds; the second and 

 thickest member of the series is termed the 

 Shinarump — a name already employed in this 

 connection by Major Powell; while the third 

 and highest member is designated the Painted 

 Desert beds. 



The Mcencopie beds are almost entirely bar- 

 ren of animal and plant remains; for apart 

 from reported fern impressions, the occur- 

 rence of which could not be verified, the only 

 evidence of plant remains were to be found 

 in a few impressions from the very base of 

 the formation, and possibly not Mcencopie at 

 all, but of an earlier horizon. These pre- 

 sented little evidence of structure, though 

 they seemed to represent the characteristics 

 of coniferous twigs and short branches, pos- 

 sibly of an Araucarian type. 



The Shinarump formation within which the 

 remains of trees are chiefly found, is separable 

 into a lower or Lithodendron member, and an 

 upper or Lereux member — ^the former em- 

 bracing conglomerates, sandstones, clay and 

 argillaceous shales forming brilliantly colored 

 banded cliffs, while the latter consists at its 

 base of a somewhat similar formation upon 

 which are superimposed beds of sandstone, 

 limestone, mortar beds with flints and cal- 

 careous marls. Apart from silioified tree 

 trunks, the only observable plant remains 

 consist of raised casts of twigs lying in all 

 positions, and stems with whorled branches, 

 all of which show Araucarian structure. 

 These forms occur on the faces of sandstone 

 rocks and shales, and they are provisionally 

 designated as Araucarites shinarumpensis. 

 The figures given of this material do not lead 

 one to hope for any very definite knowledge 

 of the plants they represent. The logs de- 

 rived from the silicified trunks of trees do not, 

 in all probability, represent the original dis- 

 tribution of the forest, since, as shown in the 



original report (op. cii.), there is evidence that 

 they were drifted some distance before being 

 laid down ; and in spite of previous statements 

 to the contrary, there is little evidence to show 

 that any of them are erect and in situ except 

 in the variegated marls just above the con- 

 glomerates, where a very careful examination 

 led to the conclusion that a group of twenty 

 or more stumps were actually in the places of 

 original gTowth, although in a sedimentary 

 bed. Many of the smaller buttes appear to 

 have been developed by reason of the logs 

 which weighted down the underlying marls 

 and tended to prevent the latter from being 

 blown or washed away, with the result that 

 such logs may now be seen lying on the tops 

 of the buttes, down the slopes of which the 

 disintegrating material is continually rolling. 



One remarkable specimen which requires 

 further explanation, is met with in certain 

 remains designated as Araucarites monilifer, 

 in allusion to the peculiar necklace-shaped 

 rows of resin drops which occur in the in- 

 terior of the trunks, where they may often be 

 seen in considerable numbers. According to 

 the facts obtained, these bodies which have a 

 stratiated surface, are resinous exudations 

 into the interior of the stem, much as resin 

 blisters are formed in the outer bark of the 

 common balsam fir. 



In the Painted Desert formation, the only 

 remains of trees appear to be represented by 

 tree trunks, the original structure of which 

 has been wholly replaced by black sand, so 

 that they resemble deposits of manganese or 

 limonite. 



The Jurassic Flora of Douglas County,. 

 Oregon, by Professor Fontaine, occupies some 

 99 pages of descriptive text and deals with no 

 less than 77 species and varieties, of which 

 fully 81 per cent, are new — the new species 

 lying chiefly among the ferns and cycads. 

 Among the conclusions to which a study of 

 these plants points, we may note as of partic- 

 ular interest that there is a remarkably large 

 proportion which are also common to the dis- 

 tant and widely separated regions of York- 

 shire, England, and eastern Siberia. Pro- 

 fessor Ward shows that there are fourteen 

 species common to the Jurassic of Yorkshire,. 



