In the following list of 41 lives, with a range in ages from 45 to 94 years, the average age is 70.7 years. Including previous lists, the average of 424 lives is 65.4 years. As shown in the following table there has been a gradual increase in this average during past years.

During an optical examination of many mesolite crystals with a view to a determination of their symmetry, the author was puzzled to find that whereas mesolite has generally been described as anorthic, on optical evidence, he could detect no trace of inclined extinction in the prism zone. A. Cavinato (1926) 1 and G. Ceshro (1909) 3 had already made similar observations. Further study revealed the probable causes of the discrepancies, and as these sources of error, and the precautions necessary for their avoidance, receive little or no mention in the principal text-books, an account of them might be of some use.

The dehydration of thomsonite has recently been studied by Mr. M. H. Hey. The work here described was carried out in the Mineralogy Department at Oxford in the years 1925 and 1926. At the suggestion of Mr. Hey the results, though inconclusive by themselves, are now published for comparison with his own, which were mostly obtained by a different method.

Mr. Arthur Russell collected in 1930 on Pim Hill, near the village of Harmer Hill, 6 miles north of Shrewsbury, Shropshire, specimens of Triassic sandstone encrusted with minute black crystals. They resemble very closely the material from Mottram St. Andrew, Cheshire, which was described and named mottramitc by Sir Henry E. Roscoe in 1876.1 Mr. Russell pointed out this resemblance and kindly placed his specimens of this rare British mineral at our disposal for investigation.