The second assistant district attorney shall receive as compensation for his services as such officer, in addition to the annual salary paid by the state, an annual salary of two thousand four hundred dollars, payable monthly on his own warrant, by the parishes comprising the Eighteenth Judicial District of Louisiana, in the following proportions:
(1) By the Parish of Iberville, the sum of eight hundred dollars.
(2) By the Parish of West Baton Rouge, the sum of eight hundred dollars.
(3) By the Parish of Pointe Coupee, the sum of eight hundred dollars.