At its southern end the western rift valley branches westwards from the trend of the main rift valley at a point just north of Lake Nyasa. Thence it continues northwards for a distance of approximately 1,000 miles, when it ends in the Sudan near Nimule.

The object of this paper is to bring before the notice of those interested a number of examples of spherulitic structures which seem to throw some light on the nature of the processes by which spherulites, lithophysae, and pyromerides are formed.

In a previous communication (1) it was shown that a temporary lowering of ocean-level, of the order of 1,000 metres, served not only to elucidate the nature of the British Quaternary strand line oscillations, but was also competent to explain the climatic changes that occurred during that period over a region that extended from North-West Europe to the pluviated lands south of the Mediterranean. It was also pointed out that a change in ocean-level of such magnitude must, being world-wide in extent, have recorded its effects in distant regions. There should, therefore, be a wide choice of areas where the hypothesis might be subjected to a critical and possibly decisive test.

Previous to 1858, the Northumberland and Durham Coalfield was considered to be destitute of any fauna other than the usual non-marine type. In 1858, J. W. Kirkby gave the first indication of marine fossils in this coalfield. He obtained specimens of Lingula credneri (Geinitz) from shales some 17 feet above the Five-Quarter seam during the sinking of a shaft at Ryhope, 3 miles south of Sunderland (9). Some of these specimens are figured by T. Davidson (2).