Inspired by this finding I'd like to know what the exative case described by Taplin for south-australian languages is or was. It does not seem to be modern terminology any longer, and lists of grammatical cases (e.g., in Wikipedia) don't have it.
With the reference given by Matthew Fulton, the Exative is the case denoting the the direction from, i.e., in more standard terminology, the Ablative. The word exative was an ad-hoc invention of George Taplin because the term Ablative was already used up for the case named today Ergative
Here's a quotation from Blake 2016, p. 138
Faced with the unfamiliar ergative case, Meyer used ‘ablative’ in Ngarrindjeri, presumably inﬂuenced by the use of the ablative to mark the agent of the passive in Latin. Taplin (1872), writing about the same language, also used ‘ablative’, but used ‘causative’ with pronouns. This use of the ablative left him in need of a label for the case expressing ‘from’ so he invented the label ‘exative’.