Plate VII. Photographs of three fragments of flags showing casts of ice crystals on the under side. All observations made on crystals of this kind indicate local differences in the forms of ice crystals presumably due to differences in the rate of freezing, in the texture of the mud and probably in variations in water content of the mud. Some crystals in the locality from which these specimens came, show pinnate secondary growths. Specimens shown here are from near the upper part of the Eagle Ford at a point about two miles north from the Chisos Mining Company's property. Brewster County, Texas. Slightly reduced. [Illustration: PLATE VII] PLATE VIII Plate VIII. Photograph of a cast made by pouring plaster over a surface of mud in which ice crystals had recently formed, in Rock Island, Illinois, after the ice in the crystals had been removed by slow natural sublimation into the atmosphere, leaving open cracks in the mud. The comb-like ridges on the plaster cast have the form of the ice crystals. Compare with Plate III. [Illustration: PLATE VIII] PLATE IX Plate IX. Photograph of a cast made by pouring plaster over a surface of mud in which ice crystals had formed, in Rock Island, Illinois, soon after the ice in the crystals had been removed by slow natural sublimation into the atmosphere, leaving open cracks in the mud. In the locality where this cast was made, the crystals were relatively slender, distant, and some gently curved, like those seen in Plate V. Slightly reduced. [Illustration: PLATE IX] PLATE X Plate X. Photograph of a cast made by pouring plaster over a surface of mud in which ice crystals had recently formed, in Rock Island, Ill., and where they had later been removed by natural sublimations into the atmosphere, leaving open cracks in the mud. It will be seen that the crystal growth in this case involves an x-like or radiating pattern formed of relatively very slender forms that almost everywhere are very gently curved somewhat reminding of the slender thread-like crystals sometimes seen in frost on windows. I have not yet seen any similar fossil crystal growths as slender as these. Slightly reduced. [Illustration: PLATE X] FOOTNOTES: [A] Strand and undertow markings, etc., New York State Museum, _Bulletin No. 196, April 1, 1917_, pp. 199-210; pl. 20-23. [B] Brick clays of Rhode Island, Massachusetts; Marbut and Woodworth, _U.S. Geol. Survey, 17th Ann. Rep., Pt. 1_, p. 992. Transcriber's Notes: Passages in italics are indicated by _underscore_. Printer's inconsistencies in spelling and punctuation have been retained. End of Project Gutenberg's Fossil Ice Crystals, by Johan August Udden