The Hepatus pudibundus (Herbst, 1785) juvenile development was studied in laboratory, under the morphological and systematical stand points. The eight early juvenile stages were obtained from larvae hatched from eggs of two ovigerous females, collected at the northern coast of the State of São Paulo, Brazil. The experiments were carried out in a climatically controlled room at 25 ± 1°C, and steady saltness of 34‰. The youngs were maintened individually and food consisted of Artemia sp. nauplii and fragments of fish muscle.The first juvenile stage were particulary drawn and described. For the remaining juvenile stages the most representative frameworks were picked out, which allowed the characterization of the first eight stages. According to juvenile morphology studies, it was noted that secondary sexual characters differentation begins from the third stage.

The study of Chasmagnathus granulata Dana 1851 was done with the setae morphology point of view. The main objective of this description was to find differents kinds of morphologicals types of setae. During this work anomalous structures were found in megalopal phase, such as: many kinds of rostral and lateral spines, as well as many kinds of spines on the telson and one kind of dorsal spine which never was cited before in the literature concerning to this specie.

They are registered for the first time in the South Brazilian coast, the crabs Mithrax hispidus (Herbst, 1790) and Mithrax tortugae Rathbun, 1920, which previous Southern limit of distribution were at São Paulo State and now it is extended to the Santa Catarina State coast line.

This paper describes the first nine juvenile stages of Cyrtograpsus angulatus Dana, 1851 obtained in laboratory conditions from three ovigerous females collected at "Molhes da Barra", Rio Grande, Brazil (32ºS and 52ºW). The main morphological features, the secondary sexual characters and the gills ontogeny were observed. Twenty one individuals reached until the ninth juvenile stage. Sexual dimorphism can be verified from the fourth juvenile stage and the number of gills are complete at the second juvenile stage.

The Lagoa do Peixe ("Peixe's Lagoon") is located between Atlantic Ocean and Lagoa dos Patos and is 30 Km long and 0,5-2,0 Km wide (31º13'S, 50º55'W -31º26'S, 51º09'). For one year, the composition and distribution of Crustácea Decapoda were analyzed monthly (from July/1994 to June/1995), in seven subareas (terrestrial border and aquatic area) and physical and chemical parameters (depth, salinity, sediment texture, oxygen in water, organic material of sediment and water temperature) were registered. Decapoda from the families Grapsidae, Ocypodidae, Portunidae (Brachyura), Diogenidae (Anomura) and Penaeidae (Penaeidea) were captured. Chasmagnathus granulata Dana 1851 was found ali months near the canal connecting Atlantic Ocean and Lagoa do Peixe, but inside the lagoon it was collected only in October/94 and June/95, and in extreme subareas it was sampled in February/95 when the salinity was 31 ‰ at these sites. Callinectes sapidus Rathbun, 1896 and Cyrtograpsus angulatus Dana, 1851 were captured throughout the year, except October/94 and April/95, respectively. Both species were found in ali áreas of sample, indicating a high plasticity in relation to the factors analyzed in this study. Another species captured probably come in the lagoon in specific months, when the environment provides ideal conditions for their develo-pments.

Uca (Minuca) burgersi Holthuis, 1967 was studied in the laboratory under the morphological and systematical stand points. One experiment was carried out involving 100 larvae, derived from one ovigerous female collected in the north coast of the State of São Paulo, Brazil. The experiment were carried out in a climatically controlled room at 25±1ºC and steady saltness of 34‰ The larvae were maintened individually and food consisted of rotifers (Brachionus plicatillis) in the first stage and Artemia sp. in the last stages. Uca (Minuca) burgersi have five or six zoeal stages and a megalopa one. All larval stages were drawn and described in detail. Tables where the morphological characteristic of each stage of the studied specie was described are also included. They were compared with the other species found in the bibliography passible of being analyzed. The comparative studies of the larval forms of each species of Uca showed that they presented a great similarity of characteristics whose specific identifications were only possible with the aid of several structures analyzed together. In the other hand, the differences among the genera of Ocypodinae occurring in Brazil are more conclusive, and can be obtained by the analyses of a few characteristics.

The larval development of Cyrtograpsus angulatus Dana, 1851 was studied in laboratory through eggs hatched from ovigerous females collected in mole of Rio Grande, Rio Grande, State of Rio Grande do Sul, Brazil. Three experiments (A, B, C) were carried out involving 250 larvae, derived from three ovigerous females. The experiments A and B, were carried in a climatically box with temperature among 22 and 25ºC, and salinity among 32 and 34‰. The experiment C in a room without controlled temperature, in a constant salinity of 30‰. The larvae were maintained individually and food consisted of rotifers Brachionus plicatillis Müller, 1786 and microscope algae Tetraselmis sp. The development of C. angulatus Dana, 1851 comprises five stages of zoea and one megalope. The main morphological characters that allow the identification of the first stages of C. angulatus, are analyzed with respect to the other Brazilian species of the family Grapsidae.