Biological aspects of Bradybaena similaris (Férussac, 1821) were studied, such as: onset of sexual maturity, occurrence of self-fertilization, oviposition, incubation period, eclosion rate and shell length measurement at different stages of development. It was noted that in isolated B. similaris the minimum and maximum time for reaching sexual maturity were 109 and 180 days, respectively. When kept in groups, the minimum time was 78 days. The occurrence of self-fertilization was observed in 18.4% of specimens. The total number of eggs per oviposition varied from one to 38 (average: 3,5 ± 7,15), the total number of eggs per mollusc varied from one to 39 (average: 7,0 ± 10,21) and the total number of oviposition per mollusc varied form one to six (averege: 2,0 ± 1,27). Thirty ovipositions (894 eggs) were followed and the minimum eclosion time of the young was 14 days, the maximum eclosion time was 35 days and the average 23,69 days. The eclosion average percent was 81,22. As to the shell length in different growth stages, it was observed that in B. similaris the length of the shell was similar until 30 days for age. After this period isolated specimens acquired a greater growth rhythm when compared to that of grouped specimens. The maximum shell length of isolated specimens was 17,4 mm whereas grouped specimens reached 14,5 mm. In this specie, individuals that were kept grouped became sexually mature earlier than isolated ones. Individuals kept isolated reach larger length of shell. In the moment of the sexual maturity, the length of the shell in the individuals tha were kept isolated was smaller than the grouped.

Biological aspects of Leptinaria unlamellata (d'Orbigny, 1835) were studied, such as: onset of sexual maturity, occurrence of self-fertilization and shell length measurement at different stages of development. In isolated specimens of L. unilamellata, sexual maturity was reached at 74 days (minimum time) and 104 days (maximum time). For the grouped specimens, the minimum time was 71 days. The occurrence of self-fertilization was observed in both species, 100% of specimens. The total numberof young per birth varied from one to 22 (average: 7,35 ± 5,78), the total number of offsprings per mollusc varied from two to eight (average: 4,1 ± 1,41) and total number of young per mollusc varied from five to 46 (average: 30,21 ± 8,08). As to the shell length in different growth stages, it was observed that in L. unilamellata, growth rhythm was similar until 15 days for age. After this period grouped specimens showed a high growth rhythm until 105 days after which the growth rhythm of grouped specimens became constant and the growth rhythm isolated specimens became greater. Grouped and isolated specimens reached a maximum size of 18,7 mm and 20,6 mm respectively. In the moment of the sexual maturity, the length of the shell in the individuals that were kept grouped was smaller than the isolated ones for L. unilamellata. In this specie individuals that were kept isolated reach larger length of shell.