摘要:

The distribution of planctonic living species of Foraminifera is conditioned by environmental factors such as temperature, salinity and oxygen content of water; thus the composition of foraminiferal faunae provides information about prevailing climatic conditions. Fossil foraminifera also can be utilized as ecological indicators, but the reconstruction of past environments becomes more and more inaccurate as we go back toward the Cretaceous period, when the group appeared. Here we present three paleoecological examples. The first one concerns the reconstruction of Mediterranean climate during Late Pleistocene. It is based on investigation on open sea sediments in which layers of volcanic ashes alternate with layers of sapropel. Both studies on relative composition in microfossils and studies on ratio between14O and16O fixed in foraminiferal shells allow to recognize climatic fluctuations. The second example deals with effects of Messinian salinty crisis in Mediterranean sea and concerns some lineages ofGloborotaliaewhich were interrupted by deposition of evaporites. The third example concerns a study on associations of planktonic Foraminifera embedded in several stratigraphic samples of Paleogene, collected in shallow and deep bottoms of Atlantic Ocean.

ISSN:0373-4137    

DOI:10.1080/11250007809440122

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The systematic position of Radiolaria and Acantharia and the theses for and against the separation into two distinct groups have been taken into consideration.

ISSN:0373-4137    

DOI:10.1080/11250007809440123

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Many studies carried out in environments polluted mainly by organic matter, point out the gradual change from biologically adapted communities to communities predominantly physically controlled where only a few well-represented species survive. However, of these factors the one concerning the nature of the bottom loses more and more of its importance in the distribution of Polychaetes and no longer has that fundamental importance which is ascribed to it as a limiting factor in biologically accomodated communities. This is an extreme example of the adaptive strategy of species with respect to the difficulties of the environment.

ISSN:0373-4137    

DOI:10.1080/11250007809440124

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The respiratory pigmentes of Polychaetes are erythrocruorins, chlorocruorins, and hemoerythrins; only erythrocruorins (Hbs) are considered here.

ISSN:0373-4137    

DOI:10.1080/11250007809440125

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The endocrinology of Nereids, though the most thoroughly investigated, cannot in its hormonal pattern be generalized for all Polychaetes. Gonadotropic principles seem to be more widespread among the species of this class. Considering the diversity of results, it is almost impossible to generalize the present knowledge on polychaete endocrinology. However, there seem to exist at least three different situations: (a) the nereid inhibitory system in monotelic epitokous species, where caudal regeneration depends on brain hormone; (b) a gonadotropic activity of brain hormone(s) in polytelic species, where caudal regeneration does not depend on brain hormone, and (c) the syllid inhibitory system which simultaneously seems to govern sexual differentiation.

ISSN:0373-4137    

DOI:10.1080/11250007809440126

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Alfei L., e Hernandez C.Ritmi di attività motoria nell'embrione di trota(Salmo trutta fario).

ISSN:0373-4137    

DOI:10.1080/11250007809440127

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue

ISSN:0373-4137    

DOI:10.1080/11250007809440121

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor