Plate III. Photograph of fossil casts of a close tangle of ice crys- 

 tals seen in a stony calcareous layer in the Eagle Ford shale in 

 Walnut Creek, about eight miles north of Austin, Texas. This tangle 

 is closer than any of the recent ice crystal marks figured hex'e, but 

 equally closely grown crystals have been seen by the writer on frozen 

 mud in Illinois. Natural size. Compare with Plate VIII. 



