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 aim of this study was to estimate the fecundity of Dilocarcinus pagei Stimpson, 1861 and Sylviocarcinus australis Magalhães & Turkay, 1996, collected in the Paraguay River, Porto Murtinho County, State of Mato Grosso do Sul, Brazil, between coordinates 21º42,000'S 57º33,649'W and 21º41,449'S 57º33,770'W, in the period of April 1999 to March 2000. After general collection procedures, the specimens were measured and processed in laboratory conditions. The river water crab species hatch like juveniles and, frequently, female specimens were observed carrying eggs in different stages of development, besides juveniles and eggs at the same time. It was apparent in the frequency distributions that D. pagei has a carapace width average greater than S. australis. The number of eggs and juveniles transported varied amongst species and amongst size class. A size superposition was observed between young and adult females for both species. According to the calculated fecundity index, D. pagei presented slightly more elevated values (7.41) than S. australis (6.65). Eggs are spherical and are not adhering to pleopods. Egg size did not varied during development, continuing with 2mm diameters.

The present work is the first report of Dardanus venosus (H. Milne Edwards, 1848) in São Paulo State and extends the range of this species in the western Atlantic farther to the south in the Brazilian region. A total of twenty two males (mean shield length: 7.56 ± 1.62 mm, 4.7 to 10.9 mm), and fifteen females (7.25 ± 2.53 mm, 4.3 to 14.5 mm) were collected in 1987, 1998, 1999 and 2000 by scuba diving from three areas of Anchieta Island (23º33'S, 45º05'W) in the Ubatuba region, and south of São Sebastião Island (23º57.8'S, 45º16'W), northern coast of São Paulo State. No ovigerous females were captured during the study period. Shells of eleven gastropod species were occupied by D. venosus: Astraea latispina (Philippi, 1844), A. olfersii (Philippi, 1846), A. phoebia Roding 1798, Calliostoma bullisi Clench & Turner 1960, Chicoreus tenuivaricosus (Dautzenberg, 1927), Cymatium parthenopeum (von Salis, 1793), Olivancillaria urceus (Röding, 1798), Phalium granulation (Born, 1778), Stramonita haemastoma (Linnaeus, 1767), Strombus pugilis Linnaeus, 1758 and Zidona dufresnei (Donovan, 1823).

The developmental stages of Dardanus insignis (Saussure, 1858) from first through eighth zoea and megalopa are described and illuslraled. The experiments were carried out involving 100 larvae, obtained from ovigerous females collected on the north littoral of the state of São Paulo, Brazil. The larvae were kept in individual containers, with water of 34‰ salinity and fed with freshly hatched nauplii of Artemia; room temperature was maintained at 25±1ºC. The larval characters of this species are compared with Dardanus arrosor (Herbst, 1796). the only species of the genus that has also heen reared in laboratory.

Six zoeal stages and the megalopa of the comestible crab Ucides cordatus cordatus (Linnaeus, 1763) are described and illustrated. The larvae were reared in the laboratory at temperature 25 ± 1ºC and water salinity of 24‰; duration of stages and survival rates were measured. Comparisons with the descriptions of the zoeal morphologic characters of Ocypodidae and Gecarcinidae permited to include definitively U. c. cordatus in the family Ocypodidae, subfamily Ocypodinae.

All the larval stages of the hermit crab Pagurus brevidactylus were studied in the laboratory, with special emphasis on external morphology and on the duration of each stage. The larvae were kept in individual containers, with water of 35‰ salinity and fed on nauplii of Artemia salina; room temperature was maintained at 24±1ºC. The post-embryonic development includes four stages of zoea and one of megalopa. All the larval stages are drawn and described in detail.