A person appointed by an agent to perform some duty, or the whole of the business relating to his agency. 2. Sub-agents may be considered in two points of view. 1. With regard to their rights and duties or obligations, towards their immediate employers. 2. As to their rights and obligations towards their superior or real principals. 3. 1. A sub-agent is generally invested with the same rights, and incurs the same liabilities in regard to his immediate employers, as if he were the sole and real principal. To this general rule there are some exceptions for example, where by the general usage of trade or the agreement of the parties, sub-agents are ordinarily or necessarily employed, to accomplish the ends of the agency, there, if the agency is avowed, and the credit is exclusively given to the principal, the intermediate agent may be entirely exempted from all liability to the sub-agent. The agent, however, will be liable to the sub-agent, unless such exclusive credit has been given, although the real principal or superior may also be liable. When the agent employs a sub-agent to do the whole, or any part of the business of the agency, without the knowledge or consent of his principal, either express or implied, the latter will only be entitled to recover from his immediate employer, and his sole responsibility is also to him. In this case the superior or real principal is not responsible to the sub-agent, because there is no privity between them. Where by an express or implied agreement of the parties, or by the usages of trade, a sub-agent is to be employed, a privity exists between the principal and the sub-agent, and the latter may justly maintain his claim for compensation, both against the principal and his immediate employer, unless exclusive credit is given to one of them; and, in that case, his remedy is limited to that party.