A branch of depression solitons with |$A=-0.2$|⁠, |$\Lambda=3$|⁠, |$\mathcal{R}=2$| and |$\tau=1.2$|⁠. We see that, as |$E_b$| is increased, the speed of the wave decreases, until eventually no depression soliton solutions are found for |$E_b>2.39$|⁠. The points |$(a)$| and |$(b)$| correspond to the solid and dashed curve in Fig. 4, respectively.