  Formation of electrostatic solitary structures are analysed for a magnetised
plasma with ion and electron thermal anisotropies. The ion thermal anisotropy
is modelled with the help of the Chew-Goldberger-Low (CGL) double adiabatic
equations of state while the electrons are treated as inertia-less species with
an anisotropic bi-Maxwellian velocity distribution function. A negative
electron thermal anisotropy $(T_{e\perp}/T_e{\parallel}>1)$ is found to help
form large amplitude solitary structures which are in agreement with
observational data.
