How send argument to Services Module (Views+Contextual filters)
When making a jQuery ajax request to a Drupal Services 3.x module REST API endpoint, define the request type of your ajax request like this. 

(function ($) {
  var request = $.ajax({
    "url" : "http://test.url/rest/viewname/555",
    "type" : "GET" 
  });
}(jQuery));


Usually a RETRIEVE request would be done using the request type GET, but for an ACTION, like the taxonomy_term Resource action selectNodes (This method returns all nodes with provided taxonomy id.), provided in Services 3.x, you would set the request type to POST. All RESTful services use POST for ACTIONs. In this case, your jQuery Ajax request would look like this:

(function ($) {
  var request = $.ajax({
    "url" : "http://test.url/rest/taxonomy_term/selectNodes",
    "type" : "POST", 
    "dataType" : "json",
    "data" : { "tid" : 555, "pager" : 0 }
  });
}(jQuery));


Each of the resource operations in a REST API use a specific HTTP Method or request type  (e.g., GET, PUT, POST, or DELETE). You need to use the correct one or it wont work. The Drupal Services 3.x module adheres to these strictly. 

To learn more about REST API request methods and how they relate to resource operations, take a look at the Using HTTP Methods for RESTful Services on the REST API Tutorial site.