200 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Walcott, C. D. 
a. Pre-Carboniferous Strata in the Grand Cafion of the Colorado, Arizona. 
Amer. Journ. Sci., Vol. XXVI., 1883, pp. 437-442, 484. 
é. The Fauna of the Lower Cambrian or Olenellus Zone. 10th Ann. Rep. 
U.S. Geol. Surv., 1890, pp. 509-760. 
c. The North American Continent during Cambrian Time. 12th Ann. Rep. 
U.S. Geol. Surv., 1891, pp. 523-568. 
d. Study of a Line of Displacement in the Grand Cafion of the Colorado, in 
Northern Arizona. Bull. Geol. Soc. Amer., Vol. L., 1890, pp. 49-64. 
e. Pre-Cambrian Igneous Rocks of the Unkar Terrane, Grand Canyon of the 
Colorado, Arizona. 14th Ann. Rep. U.S. Geol. Surv., 1894, pp. 497- 
519. 
Wheeler, G. M. 
Itinerary of Colorado Grand Canyon and River Trip of 1871, with Map. 
Engineer Dep’t U.S. Army, Rep. upon Geog. Surveys W. of 100th 
Merid. Vol. I. Geog. Report, Washington, 1589, Chap. II., pp. 147- 
171. (A brief account of all previous explorations of the Colorado 
River is here included.) 
