This paper, Constraints on primordial black holes as dark matter candidates from capture by neutron stars - http://arxiv.org/abs/1301.4984, appears to just about seal the coffin on primordial black holes as dark matter candidates. It does an admirable job summarizing the mass constraints on primordial black holes as a dark matter candidate that have appeared in the literature. Tiny black holes [<10^16 gm] were ruled out decades ago because they would have already evaporated, or be too few for consistency with observational limits on the cosmic gamma ray background. Microlensing surveys of the galactic halo have significantly constrained the number of PBH's in the mass range of 10^26 to 10^34 gm, and WMAP, COBE and FIRAS have severely constrained the number of PBH's at higher masses. Collectively, these date have left a window of opportunity for PBH's as dark matter in the range of 10^16 - 10^26 gm. The results of this paper trims the allowable mass range to within an order of magnitude of 10^25 gm. Obviously, such a narrow mass range for PBH's as dark matter candidates would invoke fine tuning problems to explain their origin.