The rock specimens described in this paper were collected by N. W. Pirie on the Cambridge Spitsbergen Expedition of 1930,1 and by the writer on the second and larger expedition of 1932. They represent an area forming the “neck” of Central Spitsbergen between Klaas Billen Bay to the south and Wijde Bay to the north, together with an area to the east and north-east of the Mittag-Leffler Glacier, extending northwards to the upper portion of the Lomme Bay Glacier, thus including the Stubendorff Mountains to the east of Wijde Bay and the western flanks of the Chydenius Range. The 1930 expedition started from the mouth of Ebba Valley in Petunia Bay and reached Wijde Bay by way of the Ebba and Mittag-Leffler Glaciers; after reconnoitring part of the Stubendorff Glacier they returned over the Mittag-Leffler and Ragnar Glaciers, passing to the north-west of Mount Hult. Most of the ground was again covered by the 1932 expedition, but in addition a sledge party reached the highland ice of Garwood Land at the head of the Ebba Glacier, turned north along the eastern margin of the Mittag-Leffler Glacier system and passing to the west of the Newton-Chernishev massif succeeded in carrying out topographical and geological observations on the Lomme Bay Glacier, though these were much curtailed by bad weather. On the return journey the party made their way down the “Vallee de Martin Conway”, crossed the divide between the Mittag-Leffler and Ebba Glaciers, and reached Petunia Bay by the same route that they had followed on the way up.