A description is given of the solar particle event of April 16, 1970, as recorded by two Vela satellites which were in the vicinity of the earth's bow shock at 18 RE. Comparison with Explorer 35 in lunar orbit indicates that the early time profile of the event was due to a spatial structure convected past the earth, and the orientation of the convected front is deduced. Anisotropies and pitch angle distributions of energetic protons are obtained from a 32-point sampling of the particle flux over the celestial sphere with a time resolution of 1 min. The net flow patterns inferred in interplanetary space reveal two reversals in the north-south component, in general alignment with the magnetic field, neither was accompanied by a magnetic field reversal. Novel features of the pitch angle distributions recorded at proton energies of ?1 MeV included (1) a narrow forward peak at 0¿ pitch angle observed in interplanetary space and accompanied by a smaller backscatter peak (we conclude that the forward peak is a real interplanetary effect uncontaminated by the presence of the bow shock). (2) accompanying this forward peak, a difference in the omnidirectional intensities at Vela 6B and at Vela 5B, of a factor of ?3, when these satellites were situated in the solar wind and in the magnetosheath, respectively, (3) a pronounced depression over approximately one hemisphere which was recorded by both Vela 6B and 5B when each was in the magnetosheath and which represents a distortion of the interplanetary pitch angle distribution due to propagation of particles into the magnetosheath.