520 PROCEEDINGS OF THE NATIONAL MUSiEUM vol.89 



Cambrian marine orj2;anisms lacked calcareous i)arts because of in- 

 sufficient calcium in the waters of that time. However, the great 

 bodies of pre-Cambrian limestone and marbles would seem to pre- 

 clude this idea. Prof. A. C. Lane considered the waters of the pre- 

 Cambrian oceans to be so acid that calcareous skeletons could not be 

 formed. Prof. Percy E. Raymond followed Brooks' theory with the 

 modification that skeletons appeared when a sluggish mode of ex- 

 istence was adopted. And, lastly, it is quite possible that the meta- 

 mori)hism of the rocks since pre-Cambrian times would acconnt for 

 most of the apparent absence, but then many of tlie strata are 

 scarcely uietamorphosed at all. Professor Raymond has elaborated 

 these various theories in his address as retiring ])resident of the 

 Paleontological Society in 1934.^ 



Although every object remotely resembling a fossil froui the oldest 

 strata of the Grand Canyon regions has been carefully collected and 

 studied, so few have been accepted as real fossils that their nnmber is 

 ahnost negligible. These few have been classified as algae, sponges, 

 and Avorm tracks, but there are students who deny that all these can 

 be proved to be of organic origin. The discovery, therefore, of an 

 imi>rint apparently of a jellyfish in the red sandstone of the Nanko- 

 weap middle group of the Grand Canyon series above the lavas 

 forming the top of the Unkar lower grou]), by C. E. Van Gundy in 

 1935, and brought to the attention of scientists by Prof. Norman E. 

 A. Hinds at the December 1937 annual meeting of the Carnegie In- 

 stitution of Washington, is of great interest provided the specimen 

 is correctly classified. Mr. Van Gundy - in 1936 published an ab- 

 sti'act of the stratigraphy of the Nankoweap group and mentioned 

 the occurrence of this medusa as suggesting a marine environment for 

 the beds containing it. The subject was discussed by Professor Hinds 

 in 1938,^ and he noted that this jellyfish is the only authenticated 

 animal fossil discovered in the Grand Canyon pre-C\imbrian, all 

 others strongly suggesting the inorganic markings found throughout 

 this series. Professor Hinds further stated the specimen had been 

 identified as ])robably a jellyfish by the present writer and that a de- 

 tailed description of it would be published later. Then, Dr. J. C. 

 Merriam, president of the Carnegie Institution, under whose leader- 

 ship the Grand Canyon researches were undertaken, presented the 

 specimen to the United States National Museum on the promise that 

 it would be described. Since making this promise, the writer has be- 

 come less certain of his first opinion as to the animal nature of the 

 specimen, which was based upon its resemblance to Brool'sella and 



I Bull. (ipol. Sof. Amer.. vol. 4G, No. 0, pp. .17."-.^02, 193.^. 



2Proc. Geol. Soc. Amer.. m.^.G, p. 304. 



" Science, new ser., vol. ,SS. No. 227S, Aug. 20. 1038. 



