We consider the synchronization problem for homogeneous networks of nonlinear SISO agents connected via diffusive partial-state coupling. The agents are non-introspective (i.e., they do not have access to their own state or output), and thus unable to manipulate their own dynamics in order to present themselves differently to the network. Moreover, the agents are not allowed to exchange additional information, such as internal controller states, over the network. Unlike many other designs for nonlinear synchronization, we do not require the agents to be passive; we rely instead on a canonical form that requires the nonlinearities to have a certain lower-triangular structure.