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New lead isotope data are presented for some late Precambrian and early Paleozoic vein and massive sulfide deposits in the Arabian Shield. Using the Stacey Kramers (1975) model for lead isotope evolution, isochron model ages range between 720 m.y. and 420 m.y. Most of the massive sulfide deposits in the region formed before 680 m.y. ago, during evolution of the shield. Vein type mineralization of higher lead content occurred during the Pan African event about 550 m.y. ago and continued through the Najd period of extensive faulting in the shield that ended about 530 m.y. ago. Late post-tectonic metamorphism may have been responsible for vein deposits that have model ages less than 500 m.y. Alternatively some of these younger model ages may be too low due to the mineralizing fluids acquiring radiogenic lead from appreciably older local crustal rocks at the time of ore formation.

As a function of training and background, there is always a dichotomy between the approach of the anatomist and that of the surgeon to anatomic informational requisites. Here is a fine text for orthopedic residents and medical students on their clinical clerkships. However, for practicing orthopedists it proves wordy and diffuse, The author frankly disclaims its usefulness as an anatomic atlas. As with any interpretive writing, it is subject to the frailties of the interpreter.In the technical view the third edition is very similar to the second. It has been shortened by 18 pages, apparently in an effort to reduce production costs. As a result, many tables have been compressed and rearranged, occasionally at the price of some clarity. Conversely, chapter headings in this third edition have been printed in red and it is a more readable version.A strength of the book is its discussions of embryology and