Benefits under prior law preserved.

(b) Notwithstanding the provisions of subsection (a) of this section, all persons receiving retirement benefits from said system on June 30, 1978, shall be eligible for an annual cost-of-living allowance in accordance with the provisions of subsection (j) of section 10-183g . (c) Any additional credited service purchased by June 30, 1978 or being purchased on that date, provided the purchase is completed in accordance with the terms of the purchase, shall be deemed to be additional credited service purchased in accordance with the provisions of this chapter.