Genève, Société Paléontologique Suisse, 1938. 4to (31.5 x 23.7 cm). 30 pp.; four fine, phototype plates, nine text figures including a page-sized graph. Later green wrappers with typed title.

A well-illustrated study, dealing with well-preserved Jurassic ammonites. Written by the Swiss palaeontologist Irène Pfaehler-Erath. It was also her thesis. Unfortunately, little else is known about her. Published in the society's Mémoires, but this seems to be an offprint. Wrapper protective rather than elegant, plates detached, but otherwise a very good, clean copy. Not in any major bibliography.