This package is intended to replace my Macintosh application Bi-De. It implements some straight-forward birth-death models for simulating phylogenies. It is intended to be fast and flexible and can simulate very large trees (depending on memory and speed of computer). It will then optionally reconstruct trees only containing extant lineages or produce trees containing a random sample of lineages. Trees can be written to a file for analysis in other packages. It will also draw lineages-through-time-plots.