Bergs of dark colour, called for convenience black and white bergs, have been observed with some frequency off the mouth of the Weddell Sea. When opportunity occurred for close examination it was found that these bergs are of two distinct varieties: one of them is the true morainic berg, in which the dark portion is quite black and opaque and consists of mud and stones which are often clearly visible; while in the other variety the dark part proves on closer approach to be translucent and of a very deep green colour, resembling that of some kinds of glass used in bottle making, and mud and stones appear to be absent. We can speak then of black and white bergs falling into two subdivisions, the morainic and the bottle-green bergs. At a distance the two kinds resemble each other very closely, and it has been found that they have some features in common. In both of them as seen by us the dark part is always smoothly rounded by water action, and in both, with few exceptions, the junction between the white and dark parts is a perfectly straight clean-cut plane. To obtain samples of either variety for examination is not an easy matter, for in the heavy swells that prevail close approach is often impossible and the surface is generally so smoothly rounded that it is extremely difficult to chip pieces from the berg. Rifle shots at close quarters have been tried without success. So far, on the Discovery Committee's ships we have not been able to collect any sample from a bottle-green berg; the only material we possess is from a morainic berg, collected by Mr. G. W. Rayner in the William Scoresby at 70? o1' S., I00? 39' W., on i February 1930, and this has been examined for us by Mr. G. H. Tipper. He reports that there are four large pebbles, of pink granite, hornfels, banded grey quartzite, and dark quartzite respectively; these specimens show few signs of ice action and are free from scratches or striae. The silt associated with the pebbles is dark grey when dried and almost black when wet; the very fine portions are composed of minute angular fragments of quartz and other minerals; the coarser material is a mixture of angular and rounded fragments of igneous and metamorphic rock. The silt is slightly calcareous, due to the presence of foraminifera and minute lamellibranchs: the foraminifera, determined by Dr. W. A. Macfadyen, are all present-day species. The presence of marine organisms with the morainic material is unusual. They may perhaps have been scraped off the sea bottom by the berg before overturning. It is more likely however that part of the sea floor has been incorporated in the parent glacier in the way suggested by Professor Debenham in his account of raised marine muds in Antarctica,' and that the berg can be described therefore as truly morainic.