摘要:

Eoplectodonta transversalis(Wahlcnberg) and other sowcrbyellids have a complex arrangement of septa in the brachial valve. It is argued that the function of these is primarily to support the lophophore and to strengthen the shell, and that the septa mirror is almost exactly the shape of the lophophore. InEoplectodonta transversalisthe ontogenetic develop ment of the lophophore varies from a simple to a complcx ptycholophe. Other plectam‐bonitaceans have trocholophous and schizolophous lophophore

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1975.tb00918.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Cretaceous and Cenozoic benthic ostracodes and their species assemblage structure have been analyzed by several different association and distribution form techniques. 425 core samples were obtained by the Deep Sea Drilling Project from 77 sites of the first 14 Legs of its survey of the world ocean floor. These analyses of 80 species from 27 composite planktic‐foraminiferal time zones representing the last 75 million years of deep‐sea faunal development revealed that a major change took place at about 40X106BP in Late Eocene or Early Oligocene, marking the time of origin of the present cold, bottom water‐mass system (psychrosphere). Prior to this world‐wide event another important, but previously unknown, ostracode fauna had been present in a wanner deep sea for at least 25 million years without significant

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1975.tb00919.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

A small, solitary rugose coral, probably belonging toAulacophyllum hemicrassatumSloss, from the Middle Devonian of Iowa, U.S.A., grew normally (conically) for three‐fourths of its length, then, in an apparent reversal of pattern, decreased in diameter so that the uppermost part of the corallum is an inverted cone. The reversal of normal growth is attributed to polyp injury or disease that gradually, rather than suddenly, decreased the polyp's ability for normal growth and skeleton buildin

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1975.tb00920.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Stromatoporoids were a subphylum of the Porifera whose soft parts can be reconstructed by comparisons with the living sclerospongesMerliaandAstrosclera. The living tissue was confined to the upper surface and penetrated only short distances into the coenosteum. Astrorhizae are traces of an excurrent water canal system that interfered with the secretion of the skeleton in some stromatoporoids but was entirely above the hard tissue in others. The stromatoporoid skeleton was composed of trabecular or spherulitic aragonite. Calcitization and dissolution of the aragonite proceeding from the centers of calcification outward account for the microstructures (fibrous, compact, tripartite, ordinicellular, cellular, melanospheric) commonly observed in the calcite skeletons of fossil stromatoporoids. Reconstructions showing the proposed relationship of the soft tissue to the hard tissue ofLabechia, Stictostroma, ActinostromaandStromatoporaare presented.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1975.tb00921.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The International Union of Geological Sciences (IUGS), founded in 1961. has developed into one of the strongest unions of the ICSU family. A composite but efficient international working structure has been organized, based on extensive voluntary efforts which are moderately yet effectively subsidized by the Union. Current developments trend towards closer cooperation with the International Geological Congress. The IUGS now covers 74 countries, although the strength in the international working structure may be contrasted with a certain lack of promotion at the national level, particularly with regard to information. This must be remedied. Geologists concerned are also encouraged to obtain their information directly through the IUGS Geological Newsletter.

ISSN:0024-1164    

DOI:10.1111/j.1502-3931.1975.tb00922.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY