ESTIMACION DE EDAD Y CRECIMIENTO EN LA "PACORA" (PLAGIOSCION SURINAMENSIS BLEECKER, 1873) POR MEDIO DE LA COMPARACION DE LOS METODOS DE ANALISIS DE DISTRIBUCION DE FRECUENCIAS Y LAS MARCAS EN ESCAMAS Y OTOLITOS

En la presente investigación se estima la edad y creecimiento de la pacora (Plagiosclon surinamensis), por medio de la comparación de los métodoe de distribución de frecuencias, marcas en las escamas y marcae en los otolitos; de esta comparación se concluye que la pacora forma tres anillos en las escamas por año y con base en este método, estableciendo los grupos de edad anuales, se calcula la ecuación de crecimiento de Von Bertalanffy, la cual se expressa de la siguiente manera:Lt (ram) = 775.1 * {1 - e -0.362 * (t - 0.0978)}. La relación talla-peso se calculó ordenando las tallas en intervalos de 10 ram y corresponde a la ecuación:Peso (gr) = 1.1 * 10-5 * L. E.(3.08), no encontrándose diferencias significativas entre el crecimiento de hembras y el de machos. Se complementa la investigación con información sobre tallas mínimas y medias de madurez sexual y espectro trófico de la especie en la parte baja de la cuenca del Río Magdalena y su plano inundable.

New and significant bird records from Rio Grande do Sul, with comments on biogeography and conservation of the southern Brazilian avifauna

I report on the occurrence of 16 species of birds in Rio Grande do Sul, southern Brazil, of which seven are new for the state - Accipiter superciliosus (Linnaeus, 1766), Brotogeris tirica (Gmelin, 1788), Hemitriccus margaritaceiventer (d'Orbigny & Lafresnaye, 1837), Phyllomyias griseocapilla Sclater, 1862, Saltator coerulescens Vieillot, 1817, Orthogonys chloricterus (Vieillot, 1819), and Sporophila lineola (Linnaeus, 1758) - and seven were previously known from unsubstantiated or poorly documented records - Ixobrychus exilis (Gmelin, 1789), Brotogeris chiriri (Vieillot, 1818), Coccyzus euleri Cabanis, 1873, Pulsatrix koeniswaldiana (Bertoni & Bertoni, 1901), Psilorhamphus guttatus (Ménétriès, 1835), Serpophaga griseicapilla Straneck, 2007, and Hemithraupis ruficapilla (Vieillot, 1818). Descriptive and natural history notes are presented for some of these species. The records of B. tirica, P. guttatus, P. griseocapilla, Myiozetetes similis (Spix, 1825), O. chloricterus, H. ruficapilla, and S. lineola represent significant southward range extensions of up to 300 km. Also, a new confirmed record of Myiarchus ferox (Statius Muller, 1776) is divulged. Finally, I argue that the Atlantic forests of north-eastern Rio Grande do Sul should be included in the Serra do Mar area of endemism (sensu SILVA et al., 2004) because of the presence of Orthogonys chloricterus, and comment on the possible range expansion of Myiozetetes similis, Sporophila lineola and other primarily tropical species in southern Brazil.

Planorbis meridaensis Preston, 1907 (Gastropoda: Planorbidae), a synonym of Biomphalaria prona (Martens, 1873)

Biomphalaria prona from Lake Valencia, Venezuela (type locality) has a polymorphic shell wich in the great majority of specimens is wider, with fewer rapidly expanding whorls, the outer one subcarinate on the left side and more or less strongly deflected leftward. Besides those modal forms there are little frequent variants characterized by narrower shell with less rapidly expanding, regularly curved whorls directed forward. Recent studies have shown that such variants constitute the predominant shell phenotype in extralacustrine populations, but are anatomically and biochemically indistinguishable from the modal class of the Lake. In the present paper it is demonstrated that the nominal species Planorbis meridaensis Preston, 1907, from Mérida, Venezuela, is identical with B. prona (Martens, 1873) of wich it must be considered a junior synonym.

História da química e da geologia: Joseph Black e James Hutton como referências para educação em ciências

The second half of eighteenth century is marked by the advancement of chemistry and geology. The first science acquired the law of conservation of mass and this science represented a important support to geology and mineralogy. We say that both became modern science that time. Our aim is to show up some interrelations between history of chemistry and history of geology by means of the study of Joseph Black's and James Hutton's works. We defend that it is positive to science education to understand and approach the relations among different and disciplinary areas of science.

Justus Von Liebig, 1803-1873. Parte 1: vida, personalidade, pensamento

This first of two papers allusive to the 200th birthday of Justus von Liebig (1803-1873) deals with the origins, life, education, ideas and influence of one of the great 19th century chemists. The principal characteristics of his "Giessen model of teaching research in chemistry" are presented, as well as the role played by many of his students in the evolution of chemical research in various countries. Liebig's strong personality, his controversies, his contribution to the chemical scene in Giessen and Munich are presented. Although few, the connections with Latin-American chemistry are focused.

David Hume e as finanças de James I

RESUMOEste artigo examina a análise de David Hume realizada em seu livro História da Inglaterra, da luta entre o parlamento e o rei James I sobre as finanças da coroa durante o primeiro trimestre do século XVII. Inicialmente, são apresentados os principais elementos políticos por trás da briga no coração do poder político da Inglaterra, seguidos por comentários do escritor escocês sobre as finanças reais, com ênfase nos seus pontos de vista sobre as receitas e despesas da Coroa durante o reinado de James I. No final são recuperados os fatores de longo prazo elencados como determinantes da nova postura parlamentar.