Unless it is interposed as an answer to the entire complaint, it must distinctly refer to the cause of action which it is intended to answer." 16

The defendant may also interpose a counterclaim as a defense, and the subject matter of the counterclaim may be legal or equitable.17

The counterclaim * * * must tend in some way to diminish or defeat the plaintiff's recovery, and must be one of the following causes of action against the plaintiff, * * * and in favor of the defendant, or of one or more defendants, between whom and the plaintiff a separate judgment may be had in the action:

1. A cause of action, arising out of the contract or transaction set forth in the complaint as the foundation of the plaintiff's claim, or connected with the subject of the action.

2. In an action on contract any other cause of action on contract, existing at the commencement of the action.18

In some of the states a cross-complaint, which is practically the equivalent of a cross-bill in chancery, is authorized.19

16 N. Y. Code Civ. Pro., Sec. 507;

Cal. Code Civ. Pro., Sec. 441. 17 N. Y. Code Civ. Pro., Sec. 501.

18 N. Y. Code Civ. Pro., Sec. 601;

Cal. Code Civ. Pro., Sec. 438.

19 Iowa, Sec. 2663.

The plaintiff may demur to the entire answer or to any separate defense in the answer containing new matter, or to any counterclaim, on the ground that such pleading is insufficient in law to constitute a defense or counterclaim,20 and where a cross-complaint is interposed by the defendant it may be demurred to on the same grounds that the defendant may demur to a complaint.