Relatively frequently found, the specimens of Homalonotinae are, in general, poorly preserved and, therefore, they are among the groups of trilobites that have so far been rather insufficiently studied. Since their occurrence is limited to the Llandovery through Middle Devonian, they may serve as a good index fossil. Their paleogeographical and correlative importance in the Upper Silurian and Lower Devonian was discussed separately (Tomczykowa, 1974).

The materials, on which the present paper is based, were collected by the writer in 1956—1958 in the Holy Cross Mts. Most of them, however, come from the boreholes managed by the Geological Institute, that is, from Goldap, Bostow, Ciepielow, Bialopole, Krowie Bagno, Lopiennik, Strzelce IG-2 and Zakrzew IG-3, as well as from the drillings of the Oil Research Survey (Malochwiej and Rozkopaczew boreholes) (Text-fig.  1). <...>

Дополнительные наблюдения за беспозвоночными (главным образом аммонитами) юрского и мелового периодов восточной Гренландии. Часть II. Некоторые инфраваланжинские аммониты из Линдеманс-фьорда, Волластон-форленд; с примечанием к основанию мелового периода

The first part of the present series of papers on the invertebrates, X chiefly ammonites, of the Jurassic and Cretaceous of East Greenland dealt with the Ilectoroceras Fauna of South-West Jameson Land; and though it was finished before war broke out in 1939, the paper was not published till eight years later.

Originated from ancient Greece, “mechanics” is a branch of science concerned with the behaviors (e.g. displacement, time, velocity, acceleration, etc.) of physical bodies subjected to actions (e.g. force, temperature, etc.). During the early modern period after the Renaissance, great scientists (e.g. Galileo, Newton, et al.) laid the laws for what is now known as “classical mechanics” that describes the motion of macro-scopic objects with velocities significantly smaller than the speed of light. By the prin-ciples of classical mechanics, if the present state of an object is detected, we are able to predict how it has moved in the past (reversibility) and how it will move in the future (determinism). <...>

We are very happy to present this two-volume book to our respected readers. It is our hope that these volumes will be of interest to all professionals in the drilling industry. It is intended for those who work in the field, at the computer, as managers in the oil industry, university professors and students, and anyone who is interested in the history of the development of drilling technologies. We believe all readers will find something useful in these volumes, both in their current and future activities. <...>