The large cell size and the success of cultivation of lung tissue made possible chromosomal studies of Taricha t. torosa, T. t. sierrae, T. g. granulosa, and T. rivularis. Explants were easily maintained under strips of Visking dialysis membrane in Rose multipurpose chambers at 26 C. Supplementing a balanced salt solution with lactalbumin hydrolysate, whole egg ultrafiltrate, and calf serum produced an adequate number of mitotic figures by the sixth or seventh day to permit an analysis of the chromosomes. All species studied had a diploid number of 22. The chromosomes were either metacentric or submetacentric. Variations in total length, as observed in the 4 idiograms, were considered to be within the distortion error introduced during the chromosomal spreading procedures. No heterologous chromosomes between male and female of each species were detected from karyotype analyses.