562 Shi I Shimer, Hervey Woodburn, 1872 Index fossils of North American; a new work based on the complete revision and reilullustration of Grabau and Shimer´ s ´´North American index fossils´´, by Hervey W. Shimer and Robert R. Shrock. A publication of the Technology press, Massachusetts institute of technology. New York, J. Wiley 1944. ix, 837 p. ilus. 28 cm. Bibliografía: p. 5-8 y notas bibliográficas al pie de las páginas