Ninety one young specimens and 3 adult females of BulI shark ("cação cabeça chata") caught in the lagoon region of Cananéia were examined, their tooth formula being 27/25 and the number of pre-caudal vertebrae ranging from 109 to 115. The proportion between the 1st and 2nd dorsal fins were found to be 2.3 and 2.8 for the young,and 2.9 to 3.1 for the adults. These data confirm that the studied form belongs to C. leuoas. Young occur regularly but in limited numbers.As regards the adults, however, females only appear during the short parturition period, i.e., from November to February. The number of embryos in the litters were from 7 to 9, their sizes ranging between 768-812 mm. The length of the smallest free young found was 697 mm, but young presumably 9 to 12 months old had 98 to 112 cm; between 21 and 24 months they were reaching 124 to 128 cm, that is, the same size they have when they start migrating to the open sea. The feeding inhibition phenomenon during the period of parturition was not observed in the female specimens caught in the lagoon. The more abundant species found in the stomach contents were: Arius spixii; Chloroscombrus chrysurus; A. grandicassus; A. barbus; Felichtys marinus; Genidens genidens; Chanophorus tajacica and Carcharhinus porosus.