we show that a recently introduced lax pair of the sawada-kotera equation is nota new one but is trivially related to the known old lax pair. using the so-called trivialcompositions of the old lax pairs with a differentially constrained arbitrary operators,we give some examples of trivial lax pairs of kdv and sawada-kotera equations.

The chromosomal spread and karyotype of Anjak (Schizocypris altidorsalis) from Hamoun Lake were determined using tissue squashing techniques with an injection of 1 mL/100 g body weight of 0.01% colchicines solution. Kidney and gill epithelia tissues were removed and used for karyotype analysis. The analysis of 145 chromosome spreads revealed the diploid chromosome number of this fish, 2n=48 and...