We have studied the electroconvective behaviour of MBBA, with initial homeotropic boundary conditions, employing a.c. fields acting transversely to the line of sight. Two major types of convective structure occur. They may be described as the distorted-homeotropic (VD) and distorted-planar (HD) states. The first bifurcation is to theVDstate and takes place at a threshold voltage which varies parabolically with the electrode-separation. The second bifurcation corresponds toVD-HDtransformation occurring close to turbulence. TheHDstructure, once nucleated, propagates in a highly organized and coherently winding manner so that an array of + 1 linear defects form at the axes of circulation. The growth speed ofHDfront is strongly voltage dependent. Field induced undulatory structures develop along theV-Hinterface below the threshold of electroconvection.