What is the black stuff between elephants' toes?"" ""Slow natives."" The slow native here is Bernard Leverson, halfway between quiet desperation and resignation in a marriage which at best ""perseveres."" His wife, Iris, has been engaging in some ""unspectacular adultery"" with an affable if not overly ardent friend. Bernard has condoned it. But he is guiltiest (and slowest) in his default toward their adolescent son Keith, on whom they have imposed an unwanted equality. And Keith, indifferent, insolent at this point, slouches around the house until he runs away from it. Bernard is also the musical examiner at a nearby convent--and the scenes which take place here, with a priest, with a nun, parallel Bernard's doubt and disaffection. This has earned Miss Astley some valid comparisons with the early Graham Greene. All of Slow Natives which deals essentially with lapsed convictions and abdicated responsibilities and which ends with a shattering scene is observed with intelligence and feeling. Her setting is Brisbane, Australia, but it is relevant anywhere. Miss Astley has won two Australian awards and has had a strong press there and in England. Her novel could but shouldn't be overlooked. She's a decisive, distinctive new writer who achieves some fine ironic effects while retaining every sympathy.