摘要:

The freshwater hoplonemertean genusProstomais critically reviewed and revised and a new speciesProstoma kolasaisp. nov., is described. All the freshwater nemerteans of the world are compared and contrasted, with reference to those common morphological characters which may be related to the colonization of freshwater habitats. A key to the world freshwater nemerteans is provided.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1976.tb00828.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Five new species from Papua New Guinea representative of five genera of astigmatous acari belonging to the family Canestriniidae are described.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1976.tb00829.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

The vertebral centra of teleost fishes are amphicoelous. They resemble biconid hour‐glass shaped cylinders, the ends of which are concave.The development, function, and design of the biconid amphicoelous shape of teleost centra are discussed in view of: the role of morphogenesis in the development of centra shape; function of the precaudal portion of the vertebral column in teleost locomotion; design of the centra as an adaptive response to functional problems.The biconid portion of the centrum is formed in compact bone by ossification within the cylindrically arranged sclerotome. The characteristic biconid shape is controlled by alternating dilation and constriction of the developing anlage, a result of differential growth of the sclerotome and notochordal sheaths. The shape of the biconid compactum is not correlated with stress distributions resulting from locomotion.Much spongy bone is present in teleost centra; it surrounds the compact biconid and forms longitudinal bars of bone along the lateral margin of the centra. Spongy bone is derived from sclerotomal mesemchyme. The time for formation, its position, and alignment of bony trabeculae within the spongy bone suggests it to be deposited in response to mechanical stresse

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1976.tb00830.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

It is argued that polymorphism is a useful broad term applicable to all forms of discontinuous variation affecting the same stages of development within populations. This unqualified term is particularly applicable when the fact of variation is known, but its causation is not known. The term “genetically determined polymorphism” is proposed for those polymorphisms where the genotype is paramount in morph determination, and where the environment is of little, if any importance (e.g. blood groups). Where the environment interacts with the genotype to elicit a particular morph the term “environmentally cued polymorphism‘ is apposite. Genetically determined polymorphisms result from discontinuously distributed, but continuously active genetic material, whilst environmentally cued polymorphisms appear to depend on universally distributed, but differentially active genetic resources.Environmentally cued polymorphism produces morphs congruent with current ecological conditions, and in fluctuating or alternating environments it avoids the worst effects of selection for the previously existing conditions. In fluctuating environments genetically determined polymorphism is a particularly costly method of achieving ada

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1976.tb00831.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Two new aphids viz.Prociphilus (Stagona) himalayaensissp. nov. infesting the roots ofPinus excelsaand an unidentified plant andCapitophorus tricholepidissp. nov. infestingTricholepis furcata,collected from Simla Himalayas and Kumaon Himalayas, respectively, of the North‐west India are describe

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1976.tb00832.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY