COSMIC-RAYS ABOVE 4 X 10(19) EV

An analysis is made of the distribution with Galactic latitude of cosm ic rays of energy above 4 x 10(19) eV from the standpoint of determini ng whether they are of Galactic or Extragalactic origin. Although it i s commonly argued that these particles are obviously extragalactic in origin, because of the near isotropy of arrival directions, in fact th is could be accommodated by assuming a Galactic origin and a compositi on of heavy nuclei. However, using new calculations of panicle traject ories for a variety of field models we argue that the measured latitud e distribution is inconsistent with this hypothesis, whatever the char ge or (reasonable) magnetic field and source distribution. Thus, these particles are indeed mainly extragalactic and are, presumably, mainly protons, although, as is pointed out, there are some problems even wi th this hypothesis.